Compositions, methods, and devices providing shielding in communications cables

ABSTRACT

Compositions, devices, and methods for providing shielding communications cables are provided. In some embodiments, compositions including electrically conductive elements are disclosed. In other embodiments, cable separators, tapes, and nonwoven materials including various electrically conductive elements are disclosed.

RELATED APPLICATIONS

This application is a continuation of U.S. Utility application Ser. No.13/795,825 filed on Mar. 12, 2013 which claims priority to U.S.Provisional Application Ser. No. 61/610,211 filed on Mar. 13, 2012, thecontent of which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

This invention relates generally to compositions, methods, and devicesfor providing shielding of communications cables.

BACKGROUND OF THE INVENTION

A broad range of electrical conductors and electrical cables areinstalled in modern buildings for a wide variety of uses. Such usesinclude, among others, data transmission between computers, voicecommunications, video communications, power transmission overcommunications cables, e.g. power over Ethernet, as well as controlsignal transmission for building security, fire alarm, and temperaturecontrol systems. These cable networks extend throughout modern officeand industrial buildings, and frequently extend through the spacebetween the dropped ceiling and the floor above. Ventilation systemcomponents are also frequently extended through this space for directingheated and chilled air to the space below the ceiling and also to directreturn air exchange. The horizontal space between the dropped ceilingand the floor above is commonly referred to as the “plenum” area.Similarly, the vertical space of the walls between the floor and theceiling include the networking of the aforementioned cable types. Thesevertical spaces are generally called the “riser” cabling space.Electrical conductors and cables extending through plenum areas aregoverned by special provisions of the National Electric Code (“NEC”).Cables intended for installation in the air handling spaces (e.g.,plenums, risers, ducts, etc.) of buildings are specifically required byNEC/CEC/IEC to pass flame test specified by Underwriters LaboratoriesInc. (UL), UL-910, or its Canadian Standards Association (CSA)equivalent, the FT-6. The UL-910, FT-6 and the NFPA 262, which representthe top of the fire rating hierarchy established by the NEC and CEC,respectively. Also applicable are the UL 1666 Riser test and the IEC60332-3C and D flammability criteria. Cables possessing these ratings,generally known as “plenum” or “plenum rated” or “riser” or “riserrated”, may be substituted for cables having a lower rating (e.g., CMR,CM, CMX, FT4, FTI or their equivalents), while lower rated cables maynot be used where plenum or riser rated cables are required.

Many communication systems utilize high performance cables. These highperformance cables normally have four or more twisted pairs ofconductors for transmitting data and receiving data. A transmittingtwisted pair and a receiving twisted pair often form a subgroup in acable having four twisted pairs. Other high performance cables caninclude coaxial cables, e.g., used singly or in conjunction with twistedpairs as a composite cable.

In a conventional cable, each twisted pair of conductors has a specifieddistance between twists along the longitudinal direction. That distanceis referred to as the pair lay. When adjacent twisted pairs have thesame pair lay and/or twist direction, they tend to lie within a cablemore closely spaced than when they have different pair lays and/or twistdirections. Such close spacing increases the amount of undesirableenergy transferred between conductors, which is commonly referred to ascross-talk. Undesirable energy may also be transferred between adjacentcables (which is known as alien crosstalk) or alien near-end cross talk(anext) or alien far-end cross talk (afext).

The Telecommunications Industry Association and Electronics IndustryAssociation (TIA/EIA) have defined standards for crosstalk, includingTIA/EIA-568 A, B, and C including the most recent edition of thespecification. The International Electrotechnical Commission (IEC) hasalso defined standards for data communication cable cross-talk,including ISO/IEC 11801. One high-performance standard for 100 MHz cableis ISO/IEC 11801, Category 5, or more recently referred to as Category5e. Additionally, more stringent standards have been implemented forhigher frequency cables including Category 6, augmented Category 6(Category 6_(A)), Category 7, augmented Category 7 (Category 7A) whichare rated for frequencies in the range of 1 MHz through 1 GHz.

There remains a need for communications cables that can operate reliablywhile minimizing or eliminating cross-talk between conductors within acable or alien cross-talk between cables, and also a need for separatorsfor use in such telecommunications cables. There also remains a need forcommunications cables that can provide low smoke generation and overallflame retardancy, as required by the “NEC” for use in plenum and riserareas of a building.

SUMMARY OF THE INVENTION

In one aspect, a pellet composition is disclosed, which includes a baseresin comprising a polymer and a plurality of electrically conductiveelements distributed within the base resin. The polymer can be, forexample, a fluoropolymer, a polyolefin, or combinations thereof. Atleast some of the electrically conductive elements can be formed atleast partially of a metal.

In this embodiment and in other embodiments disclosed herein, theelectrically conductive elements can comprise any of metal, metal oxide,or other electrically conductive materials, such as carbon nanotubes,carbon fullerenes, carbon fibers, nickel coated carbon fibers, single ormulti-wall graphene, or copper fibers, among others. By way of example,in some embodiments, the electrically conductive inclusions include anyof silver, aluminum, copper, gold, bronze, tin, zinc, iron, nickel,indium, gallium, or stainless steel. In some embodiments, theelectrically conductive inclusions can include metal alloys, such as tinalloys, gallium alloys, or zinc alloys. In other embodiments, theelectrically conductive inclusions can include metal oxides, such ascopper oxide, bronze oxide, tin oxide, zinc oxide, zinc-doped indiumoxide, indium tin oxide, nickel oxide, or aluminum oxide. In someembodiments, some of the electrically conductive inclusions are formedof one material while others are formed of another material. Further, insome embodiments, the electrically conductive inclusion are formed ofmetals and are substantially free of any metal oxides.

In some embodiments, the at least one base polymer, e.g., fluoropolymer,polyolefin, or combinations thereof, in the pellet composition comprisesat least about 50% by weight of the pellet composition, at least about60% by weight of the pellet composition, at least about 70% by weight ofthe pellet composition, at least about 75% by weight of the pelletcomposition, at least about 80% by weight of the pellet composition, atleast about 85% by weight of the pellet composition, at least about 90%by weight of the pellet composition, or at least about 95% by weight ofthe pellet composition.

In some embodiments, a weight ratio of the conductive elements to theone or more fluoropolymers or polyolefins can be in a range of about 1%to about 30%. In some embodiments the electrically conductive elementscomprise at least about 5% by weight of the pellet composition, at leastabout 7% by weight of the pellet composition, at least about 10% byweight of the pellet composition, at least about 15% by weight of thepellet composition, at least about 20% by weight of the pelletcomposition, or at least about 25% by weight of the pellet composition.

In some embodiments, the electrically conductive elements can also havea plurality of different shapes. For example, a first plurality of theconductive elements can have needle-like shapes and a second pluralityof the conductive elements can have flake-like shapes (e.g., rectangularshapes).

In some embodiments, the at least one base polymer, e.g., fluoropolymer,polyolefin, or combinations thereof, can be melt-processable at anelevated temperature. For example, the at least one base fluoropolymercan be melt-processable at an elevated temperature of at least about600° F.

In some embodiments, the at least one base polymer can be a polyolefinor a fluoropolymer. The fluoropolymer can be a perfluoropolymer, forexample, a perfluoropolymer having a melting temperature at least about600° F. For example, the perfluoropolymer can be any of FEP (fluorinatedethylene propylene), MFA(polytetrafluoroethylene-perfluoromethylvinylether) and PFA(perfluoroalkoxy).

In some embodiments, at least some of the conductive elements can beformed of a metal. In some embodiments, the metal can include, withoutlimitation, any of silver, aluminum, copper, gold, bronze, tin, zinc,iron, nickel, indium, gallium, and stainless steel. In some embodiments,at least some of the conductive elements can be formed of a metal oxide.In some embodiments, the metal oxide can include, without limitation,any of copper oxide, bronze oxide, tin oxide, zinc oxide, zinc-dopedindium oxide, indium tin oxide, nickel oxide, and aluminum oxide.

In some embodiments, the conductive elements can include a plurality ofmetallic particles having an average particle size in a range of about10 microns to about 6000 microns. For example, the conductive elementscan include a plurality of fibrils.

In another aspect, a foamable composition is disclosed, which comprisesat least one base fluoropolymer or polyolefin, a plurality ofelectrically conductive elements distributed within the at least onebase fluoropolymer or polyolefin, and a chemical foaming agentdistributed within the at least one base fluoropolymer or polyolefin. Insome embodiments, at least a portion of the electrically conductiveelements is formed of a metal. In some embodiments, the electricallyconductive elements have a plurality of different shapes. For example, afirst plurality of the conductive elements have needle-like shapes and asecond plurality of the conductive elements have flake-like shapes,e.g., rectangular shapes. In some embodiments, a first plurality of theconductive elements have a shape primarily configured to reflectelectromagnetic radiation in a range of about 1 MHz to about 40 GHz. Insome embodiments, a second plurality of the conductive elements have ashape primarily configured to dissipate electromagnetic radiation inrange of about 1 MHz to about 40 GHz.

In some embodiments of the above foamable composition having a chemicalfoaming agent, the at least one base fluoropolymer or polyolefincomprises at least about 50% by weight, or at least about 60% by weight,or at least about 70% by weight, or at least about 75% by weight, or atleast about 80% by weight, or at least about 85% by weight, or at leastabout 90% by weight, or at least about 95% by weight of the foamablecomposition. In some embodiments, the electrically conductive elementscomprise at least about 5% by weight, or at least about 7% by weight, orat least about 10% by weight, or at least about 15% by weight, or atleast about 20% by weight, or at least about 25% by weight of thefoamable composition.

In some embodiments, in the above foamable composition, the at least onebase polymer can be a polyolefin or a fluoropolymer. By way of example,the fluoropolymer can include a perfluoropolymer, e.g., FEP, MFA andPFA. In some embodiments, the foamable composition can include aperfluoropolymer that is melt-processable at an elevated temperature,e.g., at an elevated temperature of at least about 600° F.

In some embodiments, the chemical foaming agent comprises at least about2% by weight of the foamable composition. In some embodiments, thechemical foaming agent comprises at least about 3%, or at least about4%, or at least about 5%, or at least about 10%, or at least about 15%by weight of the foamable composition.

In some embodiments, wherein the chemical foaming agent comprises talc.

In some embodiments, in the above foamable composition having a chemicalfoaming agent, a weight ratio of the conductive elements to the at leastone base fluoropolymer or polyolefin is in a range of about 1 percent toabout 30 percent, e.g., in a range of about 1 percent to about 20percent, or in a range of about 1 percent to about 10 percent.

In a related aspect, a separator for use in a telecommunications cableis disclosed, which comprises a plurality of polymeric fibers assembledas a non-woven fabric, and a plurality of electrically conductiveelements distributed within the non-woven fabric. In some embodiments,the electrically conductive elements comprise at least about 5% byweight, or at least about 7% by weight, or at least about 10% by weight,or at least about 15% by weight, or at least about 20% by weight, or byat least about 25% by weight of the separator.

In some embodiments, the polymeric fibers are formed of a fluoropolymer,polyolefin, or combinations thereof. In some embodiments, thefluoropolymer can comprise a perfluoropolymer. In some embodiments, theperfluoropolymer has a melting temperature of at least about 600° F. Byway of example, the perfluoropolymer comprises any of FEP, MFA and PFA.

In some embodiments, the electrically conductive elements comprise aplurality of fibrils. In some embodiments, the fibrils include a metal.In some embodiments, the metal comprises any of silver, aluminum,copper, gold, bronze, tin, zinc, iron, nickel, indium, gallium, andstainless steel. In some embodiments, the fibrils include a metal oxide.In some embodiments, the metal oxide comprises any of copper oxide,bronze oxide, tin oxide, zinc oxide, zinc-doped indium oxide, indium tinoxide, nickel oxide, and aluminum oxide.

In some embodiments, the separator includes electrically conductiveelements having a plurality of different shapes. For example, a firstplurality of the conductive elements can have a needle-like shape and asecond plurality of the conductive elements can have a flake-like shape.In some embodiments, the separator includes a first plurality ofconductive elements having a shape configured to primarily reflectelectromagnetic radiation in a range of about 1 MHz to about 40 GHz anda second plurality of conductive elements having a shape configured toprimarily dissipate electromagnetic radiation in a range of about 1 MHzto about 40 GHz.

In some embodiments, the conductive elements comprise a plurality ofparticles having an average size in a range of about 10 microns to about6000 microns, e.g., in a range of about 10 microns to about 50 microns,or in a range of about 50 microns to about 500 microns, or in a range ofabout 500 microns to about 1000 microns.

In some embodiments, the above separator exhibits a DC conductivityalong an axial direction in a range of about 1×10³ Siemens/meter toabout 3.5×10⁷ Siemens/meter. In some embodiments, the above separatorexhibits a sheet resistance in a range of about 1×10⁻⁵ ohms per squareto about 1×10⁵ ohms per square.

Communications Cable

In further aspects, a communications cable is disclosed, which comprisesat least a pair of insulated twisted conductors, and a non-woven tapewrapped around the twisted pair of conductors, wherein the non-woventape comprises a polymer and a plurality of electrically conductiveelements distributed therein for electromagnetically shielding thetwisted pair. The polymer can be, for example, a fluoropolymer, apolyolefin, or combinations thereof.

In some embodiments, the the non-woven tape is not adapted to beelectrically grounded. In some embodiments, the non-woven tape comprisesa plurality of polymeric fibers. In some embodiments, the non-woven tapeexhibits a DC electrical conductivity along an axial direction in arange of about 1×10³ Siemens/meter to about 3.5×10⁷ Siemens/meter. Insome embodiments, the non-woven tape exhibits a sheet resistance in arange of about 1×10⁻⁵ ohms per square to about 1×10⁵ ohms per square.

In some embodiments, at least a portion of the electrically conductiveelements is formed of a metal. The metal can include, withoutlimitation, any any of silver, aluminum, copper, gold, bronze, tin,zinc, iron, nickel, indium, gallium, and stainless steel.

In some embodiments, at least a portion of the electrically conductiveelements is formed of a metal oxide. The metal oxide can include,without limitation, any of copper oxide, bronze oxide, tin oxide, zincoxide, zinc-doped indium oxide, indium tin oxide, nickel oxide, andaluminum oxide.

In some embodiments, the non-woven tape includes electrically conductiveelements having a plurality of different shapes. For example, a firstplurality of the conductive elements can have a needle-like shape and asecond plurality of the conductive elements can have a flake-like shape.In some embodiments, the non-woven tape includes a first plurality ofconductive elements have a shape configured to primarily reflectelectromagnetic radiation in a range of about 1 MHz to about 40 GHz anda second plurality of conductive elements having a shape configured toprimarily dissipate electromagnetic radiation in a range of about 1 MHzto about 40 GHz.

In some embodiments, the communications cable is an unshielded cable. Insome other embodiments, the cable is a shielded cable.

In some embodiments, the communications cable further comprises a jacketthat at least partially surrounds the non-woven tape and the twistedpair of conductors. In some embodiments, the jacket can provideshielding of the electromagnetic radiation. By way of example, thejacket can provide shielding of the electromagnetic radiation atwavelengths in a range of about 1 MHz to about 40 GHz.

Cable Jacket

In further aspects, a jacket for a cable is disclosed, which comprises apolymeric shell extending from a proximal end to a distal end andadapted for housing one or more conductors, and an electricallyconductive layer that is embedded in the polymeric shell. In someembodiments, the electrically conductive layer is adapted to provideelectromagnetic shielding of the one or more conductors.

In some embodiments, the conductors housed within the polymeric shellare adapted for transmitting digital data.

In some embodiments, the electrically conductive layer embedded in thepolymeric shell is formed of a metal. In some embodiments, the metalincludes, without limitation, any of silver, aluminum, copper, gold,bronze, tin, zinc, iron, nickel, indium, gallium, and stainless steel.

In some embodiments, the electrically conductive layer comprises acontinuous layer. In some embodiments, the electrically conductive layercomprises a checkered layer.

In some embodiments, the polymeric shell comprises a polymer. Thepolymer can be, for example, a fluoropolymer, a polyolefin, orcombinations thereof. By way of example, the fluoropolymer can be aperfluoropolymer, such as FEP, MFA or PFA.

In further aspects, a jacket for a cable is disclosed, which comprises apolymeric shell extending from a proximal end to a distal end andadapted for housing one or more conductors, and a plurality ofelectrically conductive elements distributed within the shell. In someembodiments, the electrically conductive elements have a plurality ofdifferent shapes, e.g., some of them can have a needle-like shape andsome of the others a flake-like shape.

Separators with Conductive Element

In further aspects, a separator for use in a telecommunication cable isdisclosed, which comprises a polymeric preformed elongate supportelement extending from a proximal end to a distal end and having atleast one channel adapted for receiving a plurality of conductors,wherein the elongate support element comprises at least one base polymerand a plurality of electrically conductive elements distributed in theat least one fluoropolymer. The polymer can be, for example, afluoropolymer, a polyolefin, or combinations thereof.

In some embodiments, at least some of the electrically conductiveelements are formed at least partially of a metal. In some embodiments,the electrically conductive elements have a plurality of differentshapes. For example, in some embodiments, a first plurality of theconductive elements have needle-like shapes and a second plurality ofthe conductive elements have flake-like shapes (e.g., rectangularshapes). In some embodiments, a first plurality of the conductiveelements have a shape primarily configured to reflect electromagneticradiation in a range of about 1 MHz to about 40 GHz and a secondplurality of the conductive elements have a shape primarily configuredto dissipate electromagnetic radiation in a range of about 1 MHz toabout 40 GHz.

In some embodiments, the separator exhibits a DC electrical conductivityalong an axial direction in a range of about 1×10³ Siemens/meter toabout 3.5×10⁷ Siemens/meter. In some embodiments, the separator exhibitsa sheet resistance in a range of about 1×10⁻⁵ ohms per square to about1×10⁵ ohms per square.

In some embodiments, a weight ratio of the conductive elements to theone or more polymers in the above separator is in a range of about 1percent to about 30 percent.

In some embodiments, the at least one base polymer, e.g., fluoropolymer,polyolefin, or combinations thereof, comprises at least about 50% byweight, or at least about 60% by weight, or at least about 60%, or atleast about 70%, or at least about 75%, or at least about 80%, or atleast about 85%, or at least about 90%, or at least about 95% of theseparator.

In some embodiments, the electrically conductive elements comprise atleast about 5% by weight, or at least about 7% by weight, or at leastabout 10% by weight, or at least about 15% by weight, or at least about20% by weight, or at least about 25% by weight of the separator.

In further aspect, a separator for use in a cable is disclosed, whichcomprises a polymeric structure axially extending from a proximal end toa distal end and configured to provide at least two channels each ofwhich is adapted for receiving one or more conductors. An electricallyconductive element is embedded in the polymeric structure to provideshielding between conductors disposed in the at least two channels.

In further aspects, a separator for use in a cable is disclosed, whichcomprises a polymeric structure axially extending from a proximal end toa distal end and configured to provide at least two channels each ofwhich is adapted for receiving one or more conductors, and anelectrically conductive layer formed on at least a portion of an outersurface of the polymeric structure. In some embodiments, theelectrically conductive layer is formed by a process of electrolessplating. In some embodiments, the electrically conductive layercomprises a continuous layer while in other embodiments, theelectrically conductive layer comprises a checkered layer.

Further understanding of various aspects of the invention can beachieved by reference to the following detailed description inconjunction with the associated drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 schematically depicts a plurality of pellets according to anembodiment of the invention;

FIG. 2A schematically depicts a separator according to an embodiment ofthe invention;

FIG. 2B schematically depicts a cross-sectional view of the separator ofFIG. 2A taken along line A-A;

FIG. 3A schematically depicts a needle-like conductive inclusion havingan elongated shape suitable for use in some implementations of theseparator of FIGS. 2A and 2B;

FIG. 3B schematically depicts a flake-like conductive inclusion having apancake-like shape suitable for use in some implementations of theseparator of FIGS. 2A and 2B;

FIG. 4 schematically shows a method for measuring electricalconductivity of a separator according to the teachings of the inventionin which a plurality of electrically conductive inclusions areincorporated;

FIG. 5 schematically depicts a separator and a plurality of conductorsdisposed in longitudinal channels provided by the separator;

FIG. 6A schematically depicts an unshielded cable in accordance with anembodiment of the invention;

FIG. 6B schematically depicts an unshielded cable in accordance with anembodiment of the invention;

FIG. 7 is a flow chart of an exemplary method of manufacturing acellular article, such as a separator, according to an embodiment of theinvention;

FIG. 8A schematically depicts a separator having a metal coatingdisposed on an external surface thereof according to an embodiment ofthe invention;

FIG. 8B schematically depicts a separator having a patchwork of metalportions disposed on an external surface thereof according to anembodiment of the invention;

FIG. 9 schematically depicts a separator having an electricallyconductive strip disposed therein according to an embodiment of theinvention;

FIG. 10A schematically depicts a cross-sectional end view of a separatorhaving T-shaped flap portions according to an embodiment of theinvention;

FIG. 10B schematically depicts a cross-sectional end view of a separatorhaving flap portions when the flaps are open according to an embodimentof the invention;

FIG. 10C schematically depicts a cross-sectional end view of a separatorhaving flap portions when the flaps are closed according to anembodiment of the invention;

FIG. 10D is an enlarged detail of a portion of the separator depicted inFIG. 10C according to an embodiment of the invention;

FIG. 10E schematically depicts a cross-sectional end view of a separatorhaving open channels according to an embodiment of the invention;

FIG. 10F schematically depicts a cross-sectional end view of a separatorhaving substantially closed channels according to an embodiment of theinvention;

FIG. 10G schematically depicts a cross-sectional end view of a separatorhaving offset arms according to an embodiment of the invention;

FIG. 10H schematically depicts a cross-sectional end view of a separatorhaving T-shaped arms according to an embodiment of the invention;

FIG. 11 schematically depicts a tape including a plurality of conductiveinclusions according to an embodiment of the invention;

FIG. 12 is a flow chart of an exemplary method of manufacturing acellular article, such as a tape, according to an embodiment of theinvention;

FIG. 13A schematically depicts a multi-layer tape including a polymericsubstrate and a metallic layer, according to an embodiment of theinvention;

FIG. 13B schematically depicts a multi-layer tape including a polymericsubstrate, a nonwoven fabric layer, and a metallic layer, according toan embodiment of the invention;

FIG. 13C schematically depicts a multi-layer tape including a polymericsubstrate, a metallic layer, and a nonwoven fabric layer, according toan embodiment of the invention;

FIG. 13D schematically depicts a multi-layer tape including a metalliclayer, and a nonwoven fabric layer, according to an embodiment of theinvention;

FIG. 14 schematically depicts a nonwoven material including a pluralityof conductive fibrils according to an embodiment of the invention;

FIG. 15A schematically depicts an exemplary embodiment of aneedlepunching apparatus according to an embodiment of the invention;

FIG. 15B schematically depicts an exemplary embodiment of a calenderbonding apparatus according to an embodiment of the invention;

FIG. 16 schematically illustrates a cable including a tape in accordancewith an embodiment of the invention;

FIG. 17A schematically depicts a cable jacket according to an embodimentof the invention;

FIG. 17B schematically depicts a cross-sectional view of the cablejacket of FIG. 14A taken along line A-A;

FIG. 18A schematically depicts a cable jacket having a metal layerembedded therein according to an embodiment of the invention;

FIG. 18B schematically depicts a cable jacket having a discontinuousmetal layer embedded therein according to an embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the compositions, devices, and methods disclosedherein. One or more examples of these embodiments are illustrated in theaccompanying drawings. Those skilled in the art will understand that thesystems, devices and methods specifically described herein andillustrated in the accompanying drawings are non-limiting exemplaryembodiments and that the scope of the present invention is definedsolely by the claims. The features illustrated or described inconnection with one exemplary embodiment may be combined with thefeatures of other embodiments. Such modifications and variations areintended to be included within the scope of the present invention.

So that the invention may more readily be understood, certain terms arefirst defined.

As used herein, the terms “about” or “approximately” for any numericalvalues or ranges indicate a suitable dimensional tolerance that allowsthe composition, part, or collection of elements to function for itsintended purpose as described herein. These terms indicate a ±10%variation about a central value.

The term “non-woven fabric” is used herein consistent with its commonusage in the art to refer to a material, such as sheet or web structure,made from fibers that are bonded together by chemical, mechanical, heatof solvent treatment (e.g., by entangling the fibers), which are neitherwoven or knitted.

The term “fibril” as used herein refers to a small slender filamenthaving a length equal or less than about 200 microns and an aspect ratiodefined as a ratio of length to width that is equal to or greater thanabout 100.

The term “fluoropolymer” is used herein consistent with its common usagein the art to refer a polymer having at least one monomer that includesat least one fluorine atom.

The term “per(halo)polymer” is used herein consistent with its commonusage in the art to refer to a fluoropolymer that includes monomers inwhich substantially all hydrogen atoms have been replaced with halogenatoms (e.g., fluorine, chlorine or bromine atoms).

The term “perfluoropolymer” is used herein consistent with its commonusage in the art to refer to a fluoropolymer in which substantially allhydrogen atoms have been replaced with fluorine atoms.

The term “electrically conductive material” as used herein refers to amaterial that exhibits an electrical surface resistivity less than about50 ohms per square or a volume resistivity less than about 40 ohms-cm.

The term “inclusion” as used herein refers to a material that is atleast partially contained within another material.

The term “needle-like” as used herein refers to the art recognized useof the term for a shape having a high aspect ratio, e.g., an aspectratio greater than about 75.

The term “nucleating agent” as used herein refers to a material that canact as a nucleation site that facilitates foaming.

The term “cross-talk” is used herein consistent with its common usage inthe art to refer to electromagnetic interference between conductors,cables, or other electronic circuit elements.

The present application relates generally to compositions, methods anddevices for providing shielding of communications cables. For example,the various compositions, methods and devices of the invention can beutilized to reduce or eliminate cross-talk between conductors within acable or alien cross-talk between cables. As discussed in more detailbelow, in some aspects of the invention various electrically conductiveelements or electrically conductive materials can be blended withpolymeric materials to generate pellets, separators (includingpre-formed and non-woven separators), or other structures. Variousaspects of the invention are described in more detail in the followingsubsections:

Polymer Compositions

In one aspect, the present invention provides polymeric compositions,e.g., polymeric pellets, that include a polymer, e.g., a thermoplasticpolymer, and a plurality of electrically conductive elements that aredispersed within the polymer. In one embodiment, various electricallyconductive elements can be blended within a polymer to form thepolymeric compositions.

FIG. 1 schematically depicts a polymeric composition 1, e.g. a pellet,according to an embodiment of the invention that includes a polymer baseresin 2 in which a plurality of electrically conductive inclusions 3 aredispersed. In some embodiments, the polymer base resin includes at leastabout 50 weight percent of the composition. For example, the polymerbase resin can include about 50 to about 95 weight percent of thecomposition, or about 60 to about 85 weight percent, or about 60 weightpercent to about 80 weight percent, or about 60 weight percent to about75 weight percent, of the polymeric composition.

In some embodiments, the electrically conductive inclusions 3 caninclude about 1 weight percent to about 30 weight percent, or about 5weight percent to about 20 weight percent, or about 5 weight percent toabout 15 weight percent, or about 5 weight percent to about 10 weightpercent of the polymeric composition.

Any suitable polymer can be used to as the polymer base for forming thepolymeric composition 1. In some embodiments, melt-processable polymerssuch as polyolefins, fluoropolymers, or combinations thereof can beused. For example, a variety of fluoropolymers can be employed as thebase polymer. In some embodiments, the base polymer can include one ormore perfluoropolymers. By way of example, in some embodiments, the basepolymer can be any of MFA(polytetrafluoroethylene-perfluoromethylvinylether), FEP (fluorinatedethylene propylene), PFA (perfluoroalkoxy), PVF (polyvinyl fluoride),PTFE (polytetrafluoroethylene), ETFE (ethylene tetrafluoroethylene or(poly(ethylene-co-tetrafluoroethylene)), ECTFE (ethylenechlorotrifluoroethlyene), PVDF (polyvinylidene fluoride).

In some embodiments, the electrically conductive inclusions 3 cancomprise any of metal, metal oxide, or other electrically conductivematerials, such as carbon nanotubes carbon fullerenes, carbon fibers,nickel coated carbon fibers, single or multi-wall graphene, or copperfibers. By way of example, in some embodiments the electricallyconductive inclusions 3 include any of silver, aluminum, copper, gold,bronze, tin, zinc, iron, nickel, indium, gallium, or stainless steel. Insome embodiments the electrically conductive inclusions 3 can includemetal alloys, such as, for example, tin alloys, gallium alloys, or zincalloys. In other embodiments, the electrically conductive inclusions caninclude metal oxides, such as, for example, copper oxide, bronze oxide,tin oxide, zinc oxide, zinc-doped indium oxide, indium tin oxide, nickeloxide, or aluminum oxide. In some embodiments, some of the electricallyconductive inclusions are formed of one material while others are formedof another material. Further, in some embodiments, the electricallyconductive inclusion are formed of metals and are substantially free ofany metal oxides.

The electrically conductive inclusions 3 can have a variety of shapes.For example, in some embodiments, the electrically conductive inclusionsare in the form of discrete particles having a variety of geometricalshapes. For example, the electrically conductive inclusions can compriseparticles having any of spherical, needle-like, or flake-like shapes. Insome other embodiments, the electrically conductive inclusion 3 are inthe form of agglomerates of an electrically conductive material withouta defined geometrical shape.

The electrically conductive inclusions can have a variety of sizes andaspect ratios. By way of example, the electrically conductive inclusionscan include needle-like particles having an aspect ratio in a range ofabout 10 to about 1000. In some embodiments, the electrically conductiveinclusions can have a maximum size in a range of about 10 microns toabout 6000 microns, or in a range of about 600 microns to about 6000microns, or in a range of about 10 microns to about 600 microns. By ofexample, the electrically conductive inclusions can include needle-likeparticles having a length in a range of about 10 microns to about 6000microns or in a range of about 600 microns to about 6000 microns, or ina range of about 10 microns to about 600 microns. Alternatively or inaddition, the electrically conductive inclusions can include sphericalparticles having a diameter in a range of about 10 microns to about 6000microns, or in a range of about 600 microns to about 6000 microns, or ina range of about 10 microns to about 600 microns. In other embodiments,the electrically conductive inclusions can include flake-like particleshaving a maximum cross-sectional dimension in a range of about 10microns to about 6000 microns, or in a range of about 600 microns toabout 6000 microns, or in a range of about 10 microns to about 600microns.

In some embodiments, the electrically conductive inclusions can includeparticles of different shapes. For example, the electrically conductiveinclusions can include particles having two different shapes. In somesuch embodiments, one type of the particles are particularly suitablefor reflecting electromagnetic radiation incident thereon, e.g.,electromagnetic radiation having a frequency in a range of about 1 MHzto about 40 GHz or in a range of about 1 MHz to about 10 GHz, or in arange of about 1 MHz to about 2 GHz, or in a range of about 1 MHz toabout 1.5 GHz, and the other type of particles are particularly suitablein dissipating (e.g., via heat generation or eddy current generation)the electromagnetic radiation incident thereon, e.g., electromagneticradiation having a frequency in a range of about 1 MHz to about 40 GHzor in a range, of about 1 MHz to about 10 GHz, or in a range of about 1MHz to about 2 GHz, or in a range of about 1 MHz to about 1.5 GHz.

For example, in some embodiments, the polymeric composition 1 caninclude a plurality of needle-like metallic particles and a plurality offlake-like metallic particles. In some such embodiments, the needle-likemetallic particles can primarily reflect the incident electromagneticradiation having one or more frequencies in a range of about 1 MHz toabout 10 GHz and the flake-like metallic particles can primarilydissipate (e.g., via absorption) the incident electromagnetic radiationhaving frequencies in a range of about 1 MHz to about 10 GHz. In somesuch embodiments, the fraction of particles having needle-like shaperelative to those having a flake-like shape, or vice versa, can beabout, e.g., 50/50, 40/60, 30/70, 20/80, or 10/90.

In another aspect, a polymeric composition is disclosed that includes abase polymer, a plurality of electrically conductive elements dispersedin the polymer, and at least one chemical foaming agent that is alsodispersed in the polymer.

In some embodiments, the base polymer can comprise at least about 50weight percent, or at least about 60 weight percent, or at least about70 weight percent, or at least about 80 weight percent, or at leastabout 90 weight percent or at least about 95 weight percent of thecomposition. The electrically conductive inclusions can in turn compriseat least about 1 weight percent, or at least about 2 weight percent, orat least about 3 weight percent, or at least about 4 weight percent, orat least about 5 weight percent, or at least about 6 weight percent, orat least about 7 weight percent, or at least about 8 weight percent, orat least about 9 weight percent, or at least about 10 weight percent, orat least about 15 weight percent, or at least about 20 weight percent ofthe composition. For example, the electrically conductive inclusions cancomprise about 1 weight percent to about 20 weight percent of thecomposition. Further, the chemical foaming agent can comprise at leastabout 1 weight percent, or at least about 2 weight percent, or at leastabout 3 weight percent, or at least about 4 weight percent, or at leastabout 5 weight percent, or at least about 6 weight percent, or at leastabout 7 weight percent, or at least about 8 weight percent, or at leastabout 9 weight percent, or at least about 10 weight percent, or at leastabout 15 weight percent, or at least about 20 weight percent, or atleast about 30 weight percent, of the composition.

A variety of polymers and metal inclusions, such as those discussedabove, can be utilized in the above polymeric compositions having achemical foaming agent. Further, a variety of chemical foaming agentscan be employed. By way of example, the chemical foaming agent caninclude, without limitation, any of magnesium carbonate, calciumcarbonate, talc, MgSiOH, sodium bicarbonate, members of the azo familyof compounds, azodicarbonamide, or other known chemical foaming agentsand combinations thereof, Further, in some embodiments, in addition toor instead of, the chemical foaming agent, the above polymericcompositions of the invention can include one or more nucleating agents.In some embodiments, the nucleating agent can comprise at least about 1weight percent, or at least about 2 weight percent, or at least about 3weight percent, or at least about 4 weight percent, or at least about 5weight percent, or at least about 6 weight percent, or at least about 7weight percent, or at least about 8 weight percent, or at least about 9weight percent, or at least about 10 weight percent, or at least about15 weight percent, or at least about 20 weight percent, or at leastabout 30 weight percent, of the composition. A variety of nucleatingagents can be employed. For example, in some embodiments, the nucleatingagent can be any of boron nitride, titanium dioxide, talc, nanoclays,other known nucleating agents, and combinations thereof. In someembodiments, the chemical foaming agent can also function as anucleating agent. By of way of example, U.S. Pat. No. 7,968,613 titled“Compositions for compounding, extrusion and melt processing of foamableand cellular fluoropolymer,” which is herein incorporated by referencein its entirety, teaches that talc can function both as a chemicalfoaming agent and a nucleating agent when blended in melt-processablepolymers, as such polyolefins, fluoropolymers, or perfluoropolymers.

Further, in some embodiments, the metal inclusions themselves canfunction as nucleating agents for providing nucleating sites for foamingof the above polymeric composition.

A variety of techniques can be employed to form the above polymericcompositions. In some embodiments, a base polymer, e.g., a basefluoropolymer (e.g., PVDF, PVF, ECTFE, or ETFE), or a perfluoropolymer(e.g., FEP, MFA or PFA) can be melted by exposure to an elevatedtemperature, e.g., a temperature of at least about 600 F, and theelectrically conductive inclusions, e.g., metal particles, can beblended in the melted base polymer. Further, in some embodiments, achemical foaming agent and/or a nucleating agent can also be blended inthe melted base polymer. In some embodiments, the blend can then bepellitized. For example, an extruder, e.g., a twin-screw extruder, canbe used to melt, blend and pelletize the polymer compositions. Thedesign of the extruder can be such that there is sufficient heat andmechanical energy to fully thermally melt the polymer composition withproper distribution and dispersion during mixing for homogeneity, butyet mild enough to keep the processing temperature of the compositioncompound below that in which foaming occurs. The composition can bestrand extruded and pelletized or alternatively an underwaterpelletizing technique may be used.

The above polymeric compositions can be processed to form variousarticles. Some examples of such articles include, without limitation,woven and non-woven fabrics, pre-formed and tape separators, insulativecoating for electrical conductors, among others.

A variety of processing methods can be employed to process the abovepolymeric compositions to form the above articles. For example, in someembodiments, polymeric pellets according to the teachings of theinvention, such as those discussed above, can be extruded to form avariety of articles. For example, in some embodiments, pellets havingboth metal inclusions and a chemical foaming agent can be extruded toform cellular articles.

In the following sections, a variety of articles that can be formed byusing polymeric compositions according to the teachings of the inventionare discussed.

Separators

In one aspect, the invention provides separators, e.g., for use intelecommunications cables, that include a plurality of electricallyconductive inclusions, e.g., metal particles, that are distributedtherein to provide shielding of electromagnetic radiation. In someembodiments such separators can be formed into predefined shapes, e.g.,by extrusion via a die. For example, a die with a cross-shaped openingcan be used to form an elongated separator that has an elongatedcross-shaped form. In other embodiments, the separators can be in theform of flexible tapes.

By way of example, FIGS. 2A and 2B schematically depict a pre-formedseparator 10 according to one embodiment of the invention that has anelongated cross-shaped form, which extends from a proximal end 20 to adistal end 30. The separator 10 provides four elongated channels 40A,40B, 40C, 40D, in each of which a conductor, e.g., a twisted-pair wire,can be disposed. A plurality of metal inclusions 50 are distributedthroughout the separator 10. While in some embodiments the metalinclusions 50 are distributed substantially uniformly within the body ofthe separator 10, e.g., as depicted in the cross-sectional view of FIG.2B, in other embodiments, the spatial distribution of the metalinclusions can be non-uniform. By way of example, in some embodiments,the density of the metal inclusions 50 in the proximity of the channelwalls of the separator can be greater than a respective density in thecentral portion of the separator. As discussed in more detail below, themetal inclusions facilitate shielding the conductors disposed in thechannels from one another, thereby minimizing and preferably eliminatingcross-talk between these conductors. In many embodiments, the separator10 is particularly effective in lowering the cross-talk in a frequencyrange of about 1 MHz to about 40 GHz, or in a range of about 1 MHz toabout 10 GHz, or in a range of about 1 MHz to about 2 GHz, or in a rangeof about 1 MHz to about 1.5 GHz between the conductors disposed inneighboring channels. In other embodiments, the separator 10 isparticularly effective in lowering cross-talk in a frequency range ofabout 500 MHz to about 1 GHz, in a range of about 500 MHz to about 10GHz, in a range of about 1 MHz to about 40 GHz, in a range of about 1MHz to about 10 GHz, in a range of about 1 MHz to about 2 GHz, or in arange of about 1 MHz to about 1.5 GHz. These frequency ranges areparticularly useful for separators in cables used for high speedtransmission of information. For example, to transmit informationthrough a cable at a higher bit rates, a higher bandwidth is requiredwhich, in turn, requires transmission of signals at higher frequencies.Current data cabling performance requirements are defined byANSI-TIA-568-C.2. One performance requirement for communications cablesis known as “attenuation to crosstalk ratio, far end” (ACRF). ACRF is ameasure of how much signal is received at the far end of a given cableas a ratio of the interfering signal induced by adjacent conductor pairsin the cable. Table 1, below, lists the minimum ACRF for Category 5e,Category 6, and Category 6A cables.

TABLE 1 Cable Type Highest Frequency Defined (MHz) Minimum ACRF (dB)Category 5e 100 23.8 Category 6 250 19.8 Category 6A 500 13.8

Improved reduction of cross talk between conductors in a cable canenable data transmission at higher frequencies than those listed inTable 1. For example, cables the incorporate the separators, tapes, andother materials according to embodiments of the invention can reducecross talk at a given frequency, raising ACRF and thereby enabling highperformance cable properties.

In this exemplary embodiment, the separator 10 is formed of a polymericmaterial in which a plurality of metal inclusions 50, e.g., metallicparticles, are distributed. By way of example, in some implementations,the separator 10 comprises a polyolefin, a fluoropolymer (e.g., PVDF,PVF, ECTFE, or ETFE), or a perfluoropolymer (e.g., FEP, MFA or PFA), andthe metal inclusions include a metal such as copper, silver, gold,aluminum, bronze, tin, alloys of tin, zinc, alloys of zinc, iron,nickel, indium, alloys of indium, gallium, alloys of gallium, orstainless steel. In other embodiments, the inclusions include of metaloxides, such as, for example, copper oxide, bronze oxide, tin oxide,zinc oxide, zinc-doped indium oxide, indium tin oxide, nickel oxide, oraluminum oxide. In some implementations, the separator comprises two ormore different polymers, such as two or more different polyolefinsand/or fluoropolymers, e.g., a blend of two of more of FEP, MFA, andPFA. Further, in some cases, the metal inclusions can exhibit a varietyof different shapes and/or be formed of different metals.

In some embodiments, one type of the metal inclusions primarily reflectelectromagnetic radiation within a frequency range (e.g., a frequencyrange of about 1 MHz to about 10 GHz) incident thereon while the othertype of metal inclusions primarily absorb the incident radiation in thatfrequency range. In this manner, effective shielding of conductors,e.g., twisted-pair wires, housed in the separator can be achieved.

By way of example, in this exemplary embodiment, the metal inclusions 50can include two types, one of which exhibits a needle-like shape and theother a flat flake-like shape. By way of illustration, FIG. 3Aschematically depicts one of the needle-like metal inclusions 50 a thatexhibits an elongated (needle-like) shape. In some embodiments, theneedle-like metal inclusions 50 a can have an average length (L) in arange of about 10 microns to about 6000 microns, or in a range of about10 microns to about 200 microns, or in a range of about 600 microns toabout 1000 microns (the average length can be an average of the lengthsof an ensemble of needle-like particles distributed within theseparator). In some embodiments, the needle-like metal inclusions 50 acan exhibit an aspect ratio greater than about 75, or in a range ofabout 75 to about 200. The aspect ratio can be defined as the ratio ofthe length of the inclusion relative to a maximum cross-sectionaldimension thereof, e.g., a maximum width (W) shown in FIG. 3A

FIG. 3B schematically depicts one of the flake-like metal inclusions 50b depicting a pancake-like shape that can be characterized by a maximumcross-sectional dimension (W) and a thickness (T). In some embodiments,the flake-like metal inclusions 70 distributed throughout the separator10 can exhibit an average maximum cross-sectional dimension in a rangeof about 10 microns to about 6000 microns, or in a range of about 600microns to about 6000 microns, or in a range of about 10 microns toabout 600 microns and an average length in a range of about 10 micronsto about 6000 microns, or in a range of about 600 microns to about 6000microns, or in a range of about 10 microns to about 600 microns.

In some embodiments, the metal inclusions 50 can comprise a volumefraction of the separator 10 in a range of about 1% to about 40%, or ina range of about 2% to about 30%, or in a range of about 3% to about20%, or in a range of about 4% to about 15%, or in a range of about 5%to about 10%.

In some embodiments, the polymer, e.g., fluoropolymer, polyolefin, orcombinations thereof, can comprise at least about 30%, or at least about40%, or at least about 50%, or at least about 60%, or at least about70%, or at least about 80%, or at least about 85%, or at least about90%, or at least about 95%. of the volume of the separator.

In some embodiments, the metal inclusions 50 can comprise a weightpercent of the separator in a range of about 1% to about 30%, or in arange of about 5% to about 20%, or in a range of about 5% to about 15%,or in a range of about 10% to about 15%.

In some embodiments, the polymer, e.g., fluoropolymer, polyolefin, orcombinations thereof, can comprise at least about 30 weight percent, orat least about 40 weight percent, or at least about 50 weight percent,or at least about 60 weight percent, or at least about 70 weightpercent, or at least about 80 weight percent, or at least about 85weight percent, or at least about 90 weight percent, or at least about95 weight percent, of the separator.

In some embodiments, the separator 10 exhibits an axial DC (directcurrent) electrical conductivity that is in a range of about 1×10³Siemens/meter to about 3.5×10⁷ Siemens/meter Such an axial DC electricalconductivity (σ) can be measured between the proximal end and the distalend of the separator 10 by applying a DC voltage (V) between theproximal and distal ends of the separator, e.g., by employing a voltagesource 60, and measuring the DC current (I) flowing axially (i.e., in adirection from the proximal end to the distal end or vice versa) byusing a DC current meter 64, as shown schematically in FIG. 4. Ohm's lawcan then be utilized to determine the DC electrical conductivityaccording to the following relation:

$\begin{matrix}{\sigma = \frac{I}{V}} & {{Eq}.\mspace{14mu} 1}\end{matrix}$

wherein,

σ denotes electrical conductivity,

V denotes DC voltage applied across the separator,

and I denotes DC current flowing through the separator in response toapplication of the voltage V.

In some embodiments, the separator 10 exhibits an AC (alternatingcurrent) conductivity (σ_(ac)) defined as the inverse of AC impedance)in a range of about 1×10³ Siemens/meter to about 3.5×10⁷ Siemens/meterfor frequencies in a range of about 1 MHz to about 40 GHz. The ACconductivity can be measured by applying an AC voltage axially acrossthe separator (e.g., between the proximal end 20 and the distal end 30)and measuring the AC current through the separator 20 by using an ACcurrent meter, e.g., in a manner shown in FIG. 4 with the DC voltagesource replaced with an AC voltage source and the DC current meterreplaced with an AC current meter. The AC conductivity can then bedetermined by using the following relation:

$\begin{matrix}{\sigma_{ac} = \frac{I_{\max}}{V_{\max}}} & {{Eq}.\mspace{14mu} 2}\end{matrix}$

wherein,

I_(max) denotes the maximum of the measured AC current and

V_(max) denotes the maximum of the measured AC voltage.

In some embodiments, the materials used to form the separator 10 canexhibit a sheet resistance in a range of about 1×10⁻⁵ ohms per square toabout 1×10⁵ ohms per square, or preferably about 10 ohms per square. Asone of skill in the art will appreciate, the sheet resistance of amaterial will change depending on the thickness of the material. Forexample, sheet resistance (ohms per square) multiplied by the material'sthickness in centimeters equals the volume resistivity of the material(ohms-cm). As a result, the volume resistivity needed to achieve a givensheet resistance will depend on the thickness of the material inquestion. For example, a thicker material will provide the same volumeresistivity with a less conductive material as a thinner material thatis more conductive. As a more specific example, a tape with a thicknessof 0.0254 cm (0.010 inches) can have a volume resistivity of 0.254ohms-cm and a surface resistance of 10 ohms per square. If the thicknessof the tape is reduced to 0.0127 cm (0.005 inches), the volumeresistivity is reduced by half to 0.127 ohms-cm to achieve the samesurface resistance of 10 ohms per square.

In some embodiments, the materials used to form the separator 10 canhave a shielding effectiveness in a range of about 15 dB to about 90 dB,or in a range of about 15 dB to about 50 dB, or in a range of about 50dB to about 90 dB. Shielding effectiveness can be measured according toASTM D4935-99: Standard Test Method for Measuring the ElectromagneticShielding Effectiveness of Planar Materials, the contents of which areincorporated herein by reference.

As shown schematically in FIG. 5, in use, a plurality of conductors 84A,84B, 84C, and 84 D (herein collectively referred to as conductors 84)can be disposed in the channels 82A, 82B, 82C, 82D provided by theseparator 80. The conductors can be, for example, twisted pairs ofwires. The separator 10 minimizes, and preferably eliminates, cross-talkbetween the conductors disposed in different channels. For example, whenconductors 84A, 84B, 84C, 84D are used to transmit telecommunicationsdata at rates up to about 100 Gbits/sec, or in a range of about 1Mbit/sec to about 100 Gbits/sec, or in a range of about 1 Mbit/sec toabout 40 Gbits/sec., the metal inclusions 50, e.g., facilitateelectromagnetic shielding of the conductors disposed in neighboringchannels from one another. The shielding can in turn minimize, andpreferably eliminate, the cross-talk between the neighboring conductorsat frequencies corresponding to those emitted by the conductors, e.g.,frequencies in a range of about 500 MHz to about 1 GHz or a frequenciesin a range of about 500 MHz to about 10 GHz.

While the separator 80 has a cross-shaped cross-sectional profile, inother embodiments the separator 80 can have other shapes. Otherexemplary embodiments of separators are disclosed in US Publication No.2010/0206609, filed Apr. 6, 2010, entitled “High PerformanceSupport-Separators for Communications Cables Providing Shielding forMinimizing Alien Crosstalk,” US Publication No. 2007/0151745, filed Mar.2, 2007, entitled “High Performance Support-Separators forCommunications Cables,” US Publication No. 2008/0066947, filed Jul. 16,2004, entitled “upport Separators for Communications Cable,” and U.S.Pat. No. 7,098,405, filed May 1, 2002, entitled “High PerformanceSupport-Separator for Communications Cables,”, the teachings of whichare each incorporated herein by reference in their entirety.

While in the above separator 80, the electrically conductive inclusionsare formed of a metal, in other embodiments the inclusions 86 can beformed of a metal oxide, such as, for example, copper oxide, bronzeoxide, tin oxide, zinc oxide, zinc-doped indium oxide, indium tin oxide,nickel oxide, or aluminum oxide. In other embodiments, the electricallyconductive inclusions can be formed of carbon nanotubes, graphene,and/or fullerenes. As known in the art, carbon nanotubes are allotropesof carbon with a cylindrical nanostructure. Nanotubes are members of thefullerene structural family, which also includes the sphericalbuckyballs, and the ends of a nanotube may be capped with a hemisphereof the buckyball structure.

The separator 80 can be used in a variety of cables, including shieldedand unshielded cables. By way of example, FIG. 6A schematically depictsa shielded cable 90 in which the separator 10 is disposed. The shieldedcable 90 includes a metal braid, metal tape, or both 92 that surroundsthe separator 10 to provide shielding of alien cross-talk. In somecases, in use, the metal braid, metal tape, or both can be grounded. Themetal braid, metal tape, or both 92 is turn surrounded by a jacket 93,which can be formed of a polymeric material. In some cases, the jacketcan be formed of a low-smoke PVC, halogenated polyolefin, orzero-halogen polyolefin. In some cases, the jacket 93 is formed of apolymer, such as a polyolefin, a fluoropolymer, e.g., FEP, MFA, PFA,ETFE, ECTFE, PVDF, PVF, or combinations thereof.

By way of further illustration, FIG. 6B schematically depicts anunshielded cable 94 that incorporates the separator 10. The cable 94further includes a jacket 95 that surrounds the separator 10. In someembodiments, the jacket 95 can be in contact with the outermost tips ofthe separator 10 to provide positional stability. In other embodiments,a gap can exist between the separator and the jacket 95.

The above separator 10, or other pre-formed cellular articles, having aplurality of metal inclusions can be manufactured in a variety of ways.By way of example, with reference to the flow chart of FIG. 7, in oneexemplary method of manufacturing the separator 10, a plurality ofpolymer pellets, e.g, fluoropolymer or polyolefin pellets, in whichmetal inclusions are incorporated, such as the pellets discussed above,can be melted (step 1) and the molten pellets can be extruded to formthe separator 10 (step 2). The resulting separator can be solid or caninclude a plurality of cells, e.g., a cellular foam. For example, thecellular foam can include cells having an open cell structure, a closedcell structure, or a combination thereof. The average size of the foamcells can vary. In some embodiments the foam cells can have an averagesize in a range of about 0.0005 inches to about 0.003 inches with anaverage size of about 0.0008 inches. Further exemplary embodiments ofmethods of manufacturing separators are disclosed in U.S. applicationSer. No. 12/221,280, filed Aug. 1, 2008, entitled “Compositions forCompounding, Extrusion, and Melt Processing of Foamable and CellularFluoropolymers,” now issued as U.S. Pat. No. 7,968,613 and in U.S.application Ser. No. 12/590,471, filed Nov. 9, 2009, entitled“Compositions, additives, and compounds for melt processable, foamable,and cellular fluoroploymers,” now published as U.S. Patent PublicationNo. 2010/0072644 the teachings of both of which are incorporated hereinby reference in their entirety.

In some embodiments, rather than or in addition to distributing metalinclusions within a separator, an outer surface of a separator can becoated with an electrically conductive material, e.g. it can bemetalized, to provide electromagnetic shielding. By way of example, FIG.8A schematically depicts an embodiment of such a separator 96, which hasa polymeric body portion 98 having a T-shaped cross-sectional profile. Athin metal coating 100 covers an outer surface of the body portion 98 toprovide electromagnetic shielding. In some embodiments, a thickness ofthe metal coating can be, e.g., in a range of about 3 microns to about12 microns. While in some embodiments, the metal coating has asubstantially uniform thickness, in other embodiments, the thickness ofthe metal coating can exhibit a variation over the surface on which itis deposited. A number of metals can be utilized to form the coating100. By way of example, the metal coating can be formed of any ofcopper, silver, aluminum, copper, gold, bronze, tin, zinc, iron, nickel,indium, gallium, or stainless steel. In some embodiments, a plurality ofelectrically conductive inclusions (e.g., metal inclusions), discussedin more detail above, can be distributed within the polymeric bodyportion 98.

While in this embodiment, the metal coating 100 covers substantially theentire outer surface of the body portion 98, in other embodiments, themetal coating can cover only portions of the outer surface. By way ofexample, FIG. 8B schematically depicts a separator 97 according toanother embodiment having a metal coating that is in the form of apatchwork of metal portions 101 deposited on the outer surface of apolymeric body portion 99 of the separator. Again, the thickness of eachmetal portion can be, e.g., in a range of about 3 microns to about 12microns. In some cases, the metal portions cover at least about 30%, orat least about 40%, or at least about 50%, or at least about 60%, or atleast about 70%, or at least about 80%, or at least about 90%, or atleast about 95% of the surface area of the separator. In someembodiments, a plurality of electrically conductive inclusions, e.g.,metal inclusions, can be distributed within the polymeric body portion99.

The coating of conductive material can be applied using any suitableprocess known in the art. For example, the coating can be applied usinga process of electroless plating. Other processes that can be used toapply the coating of conductive material can includes, for example,electroplating, vacuum deposition, sputter coating, double-side plating,single-side plating. In some embodiments, the coating can be applied asa film or foil bonded or otherwise attached to or disposed on theseparator. In other embodiments, the coating can be applied by passingthe separator through a metal bath, e.g., a tin, bismuth-tin blend, orindium alloy bath.

FIG. 9 schematically depicts a separator 100 according to anotherembodiment of the invention that includes a polymeric body portion 102having a T-shaped cross section which provides 4 channels in whichconductors can be disposed. The separator 100 further includes anelectrically conductive strip 102 (e.g., a metal strip) that is disposedinternally within the body portion 101. In this embodiment, the metalstrip extends along the length of the separator from a proximal end to adistal end thereof to provide electromagnetic shielding betweenconductors (not shown) disposed within the channels formed by theseparator. In some embodiments, a thickness of the internal metal stripcan be in a range of about 6 microns to about 55 microns.

The above separator 100 can be manufactured in a variety of ways. In oneexemplary method of manufacturing the separator 100 the electricallyconductive strip 102 can be co-extruded along with a plurality offluoropolymer or polyolefin pellets to form the separator 100.

FIG. 10A schematically depicts a separator 300 according to anotherembodiment of the invention that includes a body portion 302 having arms304 that extend outward to T-shaped flap portions 305. The flap portions305 are shaped to form a plurality of channels 306 in which conductors308 can be disposed. As discussed above, the separator 300 can be formedof a polymeric material, such as, FEP, PFA, MFA, and any of the otherpolymers discussed above. Also as discussed above, a plurality of metalinclusions 310, e.g., metallic particles, can be distributed in thepolymeric material of the separator 300. In some embodiments, ashielding material 310 can be wrapped around the separator 300. Theshielding material 310 can be formed of any material, such as the tapematerials discussed in more detail below. In some embodiments, theshielding material can be an aluminum mylar film. For other embodiments,the shielding material can be a multi-layer tape material, as discussedbelow with respect to FIGS. 13A, 13B, 13C, 13D, or a nonwoven material,as discussed below with respect to FIG. 14.

FIG. 10B schematically depicts a separator 200 according to anotherembodiment of the invention that includes an inner central portion 202and outer flap portions 204. The separator 200 can be formed of apolymeric material, such as, FEP, PFA, MFA, and any of the otherpolymers discussed above. The flap portions are shaped to form aplurality of channels 206 in which conductors can be disposed. The flapportions 204 can be initially in an open position to allow insertion ofelectrical conductors, e.g., twisted pair conductors, within thechannels 206. The flap portions 204 can then be sealed (e.g., viaapplication of heat and/or pressure) as shown schematically in FIG. 10C.For example, during manufacturing, the flap portion 204 is in the openedposition (e.g., as shown in FIG. 10B) and closes as either pressure orheat or both are applied (normally through a circular cavity duringextrusion). Optionally, a second heating die may be used to ensureclosure of the flap-top after initial extrusion of the separator orcable during manufacture. Another possibility is the use of a simplemetal ring placed in a proper location that forces the flap-top downduring final separator or cable assembly once the conductors have beenproperly inserted into the channels. The metal ring may be heated toinduce proper closure. Other techniques may also be employed as themanufacturing process will vary based on separator and cablerequirements (i.e. number of conductors required, use of grounding wire,alignment within the channels, etc.). As shown in more detail in FIG.10D, in one embodiment the flap portion 208 can be secured to a recessedportion of one side of an opening of the cavity of the separator 210,and closure occurs when the unsecured, physically free end 208 isadjoined to and adhered with the other end of the outer surface of thechannel wall.

FIG. 10E schematically depicts a separator 350 according to anotherembodiment of the invention that includes substantially open channels352 in which conductors 354 can be disposed. FIG. 10F schematicallydepicts a separator 360 according to another embodiment of the inventionthat includes substantially closed channels 362. For example, the wallsof the channels can encircle the channels through an angle of about 200degrees thereby leaving openings of about 160 degrees, as shown in FIG.10E. For another example, the walls of the channels can encircle thechannels through an angle of about 350 degrees thereby leaving openingsof about 10 degrees, as shown in FIG. 10F. In some embodiments, thewalls of the channels can encircle the channels through an angle in therange of about 200 degrees to about 350 degrees thereby leaving openingsin the range of about 160 degrees to about 10 degrees.

FIG. 10G schematically depicts a separator 370 according to anotherembodiment of the invention that includes a body portion 371 having armsthat extend outward to T-shaped flap portions 373. The flap portions 373are shaped to form a plurality of channels 372 in which conductors 374can be disposed. The separator includes at least two opposing arms 375,377 that are offset from each other relative to the center of theseparator 370. In some embodiments, the offset between opposing arms375, 377 of the separator 370 can reduce interference, e.g., crosstalk,between adjacent twisted pairs of conductors by increasing the spacingbetween adjacent twisted pairs that match in their twist orientation.For example, the offset between opposing arms 375, 377 of the separator370 can provide an additional offset between twisted pairs running inadjacent channels 372 of the separator 370. The arms 375, 377 can beoffset from the center of the separator by various distances. Forexample, the arms 375, 377 can be offset from the midpoint of theseparator by a distance equal to about half the thickness of the arms375, 377. In some embodiments, the arms 375, 377 can be offset from themidpoint of the separator by a distance equal to about half the diameterof the conductors 374.

As discussed above, the separators 350, 360, 370 depicted in FIGS. 10E,10F, and 10G can be formed of a polymeric material, such as, FEP, PFA,MFA, and any of the other polymers discussed above. Further, asdiscussed above, the separators 350, 360, 370 can be solid or caninclude a plurality of cells 356, 366, 376, e.g., a cellular foam. Forexample, the cellular foam can include cells have an open cellstructure, a closed cell structure, or a combination thereof. Also asdiscussed above, a plurality of metal inclusions 370, 380, 390, e.g.,metallic particles, can be distributed in the polymeric material of theseparator 350, 360, 370. In some embodiments, a shielding material 358,368, 378 can be wrapped around the separator 350, 360, 370. Theshielding material 358, 368, 378 can be formed of any material, such asthe tape materials discussed in more detail below. In some embodiments,the shielding material can be an aluminum mylar film. For otherembodiments, the shielding material can be a multi-layer tape material,as discussed below with respect to FIGS. 13A, 13B, 13C, 13D, or anonwoven material, as discussed below with respect to FIG. 14.

Other exemplary embodiments of separators are disclosed in USPublication No. 2010/0206609, filed Apr. 6, 2010, entitled “HighPerformance Support-Separators for Communications Cables ProvidingShielding for Minimizing Alien Crosstalk,” US Publication No.2007/0151745, filed Mar. 2, 2007, entitled “High PerformanceSupport-Separators for Communications Cables,” US Publication No.2008/0066947, filed Jul. 16, 2004, entitled “Support Separators forCommunications Cable,” and U.S. Pat. No. 7,098,405, filed May 1, 2002,entitled “High Performance Support-Separator for Communications Cables,”the teachings of which are each incorporated herein by reference intheir entirety.

In some embodiments, the separator 200 can include a plurality ofelectrically conductive inclusions 215 (e.g., metal inclusions), asshown schematically in FIGS. 2A and 2B and described in more detailabove with respect to those figures. For example, in some embodiments,the central portion 202 of the separator can include a plurality ofelectrically conductive inclusions. In some embodiments, the flapportions 204 can include an electrically conductive coating or layer 217that extends along the length of that portion, e.g., as shownschematically in FIGS. 8A and 8B and described in more detail above withrespect to those figures. For example, the electrically conductive layer217 can be continuous or discontinuous. In some embodiments, the flapportions 204 of the separator 200 can include an electrically conductivecoating or layer 217 and the central portion 202 can include a pluralityof electrically conductive inclusions 215. The electrically conductivecoating or layer 217 can be disposed on the outer surface 212 of eachflap portion 204, on an inner surface 214 of the channel 206 formed bythe flap portion 204, or on both the inner surface 214 and the outersurface 212.

In another embodiment, the separator 200 can include an electricallyconductive strip 219, 221 (e.g., a metal strip). In some embodiments, anelectrically conductive strip 219 can be disposed internally within thecentral portion 202. In other embodiments an electrically conductivestrip 221 can be disposed internally within the flap portions 204. Insome embodiments, electrically conductive strips 219, 221 can bedisposed internally within both the central portion 202 and the flapportions 204. In any of these embodiments, the metal strip 219, 221 canextend along the length of the separator from a proximal end to a distalend thereof to provide electromagnetic shielding between conductors (notshown) disposed within the channels formed by the separator. In someembodiments, a thickness of the internal metal strip can be in a rangeof about 6 microns to about 55 microns.

In some embodiments, the flap portions 204 of the separator 200 caninclude an internal electrically conductive strip and the centralportion 202 can include a plurality of electrically conductiveinclusions. In other embodiments, the flap portions 204 of the separator200 can include a plurality of electrically conductive inclusions andthe central portion 202 can include an internal electrically conductivestrip. In other embodiments, the separator can include any combinationof the electrically conductive inclusions 215, the electricallyconductive layers 217, and the electrically conductive strips 219discussed above with respect to FIGS. 8A, 8B, 9, 10A 10B, 10C, and 10D.

While in some embodiments of the separators discussed above the metalinclusions are distributed substantially uniformly within the body ofthe separator, e.g., as schematically depicted in the cross-sectionalviews of FIGS. 2A and 2B, in other embodiments, the spatial distributionof the metal inclusions can be non-uniform. For example, the density ofinclusions, i.e., the number of inclusions per unit volume, in the flapportions can be greater than in the central portion. For anotherexample, the density of inclusions in the central portion can be greaterthan in the flap portions.

Tapes

As discussed above, in another aspect, the invention provides tapes,e.g., for use in telecommunications cables, in which electricallyconductive inclusions are incorporated. In some embodiments, the tapescan include a plurality of metal particles that are distributed thereinto provide shielding of electromagnetic radiation. In many embodiments,such tapes are flexible so as to be configurable into a desired shape.For example, in some embodiments a tape can be curved or bent along itslongitudinal axis so as to form a shape suitable for at least partiallysurrounding (wrapping) one or more conductors, e.g., a pair of twistedpair conductors. In some exemplary embodiments, a tape can be used as anoverall shield for a cable that includes unshielded twisted pairs (withor without internal separators, e.g., crosswebs). This type of use canbe referred to as shielded, unshielded twisted pair (“shielded UTP, or“S-UTP”). In some exemplary embodiments, a tape according to the presentteachings can be used as an overall shield for a cable having shieldedconductors, e.g., individual conductors or twisted pairs of conductors.The conductors can also be shielded using a tape according to thepresent teachings. This type of use can be referred to as shielded,individually shielded twisted pair, “shielded ISTP.” In other exemplaryembodiments, a tape can be used to shield the twisted pairs while thecable itself remains unshielded. This type of use can be referred to as“PIMF” or “PiMF,” which traditionally refers to pairs in metal foil, butcan also be used to refer to embodiments in which the tapes disclosedherein are used to shield the twisted pairs.

By way of example, FIG. 11 schematically depicts a tape 110 according toone embodiment of the invention that extends from a proximal end 103 toa distal end 104. The exemplar tape has a polymer body portion 106 inwhich a plurality of electrically conductive inclusions 112, e.g., metalparticles, are distributed.

In some embodiments, the tape 110 has a thickness less than about 0.020inches, e.g. in a range of about 0.001 inches to about 0.020 inches orin a range of about 0.001 inches to about 0.010 inches, or in a range ofabout 0.010 inches to about 0.020 inches. In some embodiments, the tapeis formed of non-woven polymeric fabric in which a plurality ofelectrically conductive inclusions, e.g., metal particles, areincorporated, as discussed in more detail below.

In some embodiments, the tape can comprise a polymer, a polyolefin, or afluoropolymer, e.g., a perfluoropolymer, such as FEP, MFA, PFA, and themetal inclusions are formed of a metal such as silver, aluminum, copper,gold, bronze, tin, zinc, iron, nickel, indium, gallium, or stainlesssteel. In some implementations, the tape can include two or moredifferent polymers, polyolefins, fluoropolymers, such asperfluoropolymers, e.g., a blend of two of more of FEP, MFA and PFA.Further, in some cases, the metal inclusions can exhibit a variety ofdifferent shapes and/or be formed of different metals.

In this embodiment, the metal inclusions 112 can include two types, oneof which exhibits a needle-like shape and the other a flat flake-likeshape, as discussed in more detail above and as schematically depictedin FIGS. 2A and 2B.

In some embodiments, the metal inclusions 112 can comprise a volumefraction of the tape 110 in a range of about 1% to about 40%, or in arange of about 2% to about 30%, or in a range of about 3% to about 20%,or in a range of about 4% to about 15%, or in a range of about 5% toabout 10%.

In some embodiments, the polymer, e.g., fluoropolymer, polyolefin, orcombinations thereof, can comprise at least about 30%, or at least about40%, or at least about 50%, or at least about 60%, or at least about70%, or at least about 80%, or at least about 85%, or at least about90%, or at least about 95% of the volume of the tape.

In some embodiments, the metal inclusions 50 can comprise a weightpercent of the separator in a range of about 1% to about 30%, or in arange of about 5% to about 20%, or in a range of about 5% to about 15%,or in a range of about 10% to about 15%.

In some embodiments, the polymer, e.g., fluoropolymer, polyolefin, orcombinations thereof, can comprise at least about 30 weight percent, orat least about 40 weight percent, or at least about 50 weight percent,or at least about 60 weight percent, or at least about 70 weightpercent, or at least about 80 weight percent, or at least about 85weight percent, or at least about 90 weight percent, or at least about95 weight percent, of the tape.

In some embodiments, the tape 110 exhibits an axial DC (direct current)electrical conductivity that is in a range of about 1×10³ Siemens/meterto about 3.5×10⁷ Siemens/meter. Such an axial DC electrical conductivity(σ) can be measured between the two points on the tape 110 by applying aDC voltage (V) between the points e.g., by employing a voltage source60, and measuring the DC current (I) flowing axially (i.e., in adirection from one point to another or vice versa) by using a DC currentmeter 64, e.g., in a manner shown in FIG. 4. Ohm's law can then beutilized to determine the DC electrical conductivity according to thefollowing relation:

$\begin{matrix}{\sigma = \frac{I}{V}} & {{Eq}.\mspace{14mu} 1}\end{matrix}$

wherein,

σ denotes electrical conductivity,

V denotes DC voltage applied across the separator,

and I denotes DC current flowing through the separator in response toapplication of the voltage V.

In some embodiments, the tape 110 exhibits an AC (alternating current)conductivity (defined as the inverse of AC impedance) in a range ofabout 1×10³ Siemens/meter to about 3.5×10⁷ Siemens/meter for frequenciesin a range of about 1 MHz to about 40 GHz. The AC conductivity can bemeasured by applying an AC voltage between two points on the tape andmeasuring the AC current through the tape 110 by using an AC currentmeter, e.g., in a manner shown in FIG. 4 with the DC voltage source 60replaced with an AC voltage source and the DC current meter 64 replacedwith an AC current meter. The AC conductivity can then be determined byusing the following relation:

$\begin{matrix}{\sigma_{ac} = \frac{I_{\max}}{V_{\max}}} & {{Eq}.\mspace{14mu} 2}\end{matrix}$

wherein,

I_(max) denotes the maximum of the measured AC current and

V_(max) denotes the maximum of the measured AC voltage.

In some embodiments, the tape 110 can exhibit a sheet resistance in arange of about 1×10⁻⁵ ohms per square to about 1×10⁵ ohms per square, orpreferably about 10 ohms per square. As one of skill in the art willappreciate, the sheet resistance of a material will change depending onthe thickness of the material. For example, sheet resistance (ohms persquare) multiplied by the material thickness in centimeters equals thevolume resistivity of the material (ohms-cm). As a result, the volumeresistivity needed to achieve a given sheet resistance will depend onthe thickness of the material in question. For example, a thickermaterial will provide the same volume resistivity with a less conductivematerial as a thinner material that is more conductive. As a morespecific example, a tape with a thickness of 0.0254 cm (0.010 inches)can have a volume resistivity of 0.254 ohms-cm and a surface resistanceof 10 ohms per square. If the thickness of the tape is reduced to 0.0127cm (0.005 inches), the volume resistivity must be reduced by half to0.127 ohms-cm to achieve the same surface resistance of 10 ohms persquare.

In some embodiments, the tape 110 can have a shielding effectiveness ina range of about 15 dB to about 90 dB, or in a range of about 15 dB toabout 50 dB, or in a range of about 50 dB to about 90 dB. Shieldingeffectiveness can be measured according to ASTM D4935-99: Standard TestMethod for Measuring the Electromagnetic Shielding Effectiveness ofPlanar Materials, the contents of which are incorporated herein byreference.

The tapes and separators discussed above can be made using anytechniques known in the art for processing polymers. In an exemplaryembodiment, the tapes and separators can be produced by extruding thepolymer compositions, as discussed above.

The above tape 110 having a plurality of electrically conductiveinclusions can be manufactured in a variety of ways. By way of example,with reference to flow chart of FIG. 12, in one exemplary method ofmanufacturing the tape 110, a plurality of polymer pellets, e.g.,fluoropolymer or polyolefin pellets, in which metal inclusions areincorporated, such as the pellets discussed above, can be melted (step1) and the molten pellets can be extruded to form the tape 110 (step 2).

FIG. 13A schematically depicts a multi-layered tape 113 according to anembodiment of the invention that includes a substrate layer 115 formedfrom a polymeric material. By way of example, in some embodiments, thesubstrate layer 115 is formed of a fluoropolymer, e.g., aperfluoropolymer. Some examples of suitable polyolefins orfluoropolymers for forming the substrate layer 115 include, withoutlimitation, FEP, MFA, PFA, PVF, PTFE, ETFE, ECTFE, PVDF, combinationsthereof, or other suitable fluoropolymers or polyolefins. In someembodiments, the polymeric substrate 115 is a foamed substrate, e.g., asubstrate having pockets of gas (e.g., air) formed therein. By way ofexample, foamed polymeric compositions and methods for forming suchcomposition are disclosed in U.S. application Ser. No. 12/221,280, filedAug. 1, 2008, entitled “Compositions for Compounding, Extrusion, andMelt Processing of Foamable and Cellular Fluoropolymers,” now issued asU.S. Pat. No. 7,968,613, the teachings of which are incorporated hereinby reference, can be employed in some embodiments for generating thepolymeric substrate 115. Alternatively, in some other embodiments, thepolymeric substrate 115 can be a solid substrate. In other embodiments,the polymeric substrate can be a non-woven polymeric fabric, asdiscussed in more detail below. In some embodiments, the thickness ofthe substrate layer can be less than about 0.020 inches, e.g. in a rangeof about 0.001 inches to about 0.020 inches or in a range of about 0.001inches to about 0.010 inches, or in a range of about 0.010 inches toabout 0.020 inches, though other thicknesses can also be utilized.

The polymeric substrate 115 can be electrically insulative, dissipativeor conductive. In some embodiments, the polymeric substrate 115 includesa plurality of electrically conductive inclusions (e.g., metalinclusions) distributed therein, e.g., in a manner discussed above. Insome embodiments the density of the electrically conductive (e.g.,metal) inclusions are sufficiently high such that the inclusions form aninterconnected network to form, e.g., an electrically conductivepolymeric substrate. In other embodiments the density of the metalinclusions can be less such that the inclusions are substantiallyseparated from one another to form, e.g., a dissipative polymericsubstrate.

The multi-layered tape 113 can further include a thin metallic layer 117(e.g., an aluminum foil layer in this implementation) that is disposedover a surface of the underlying substrate 115. The thin metallic layercan have a thickness, e.g., in a range of about 50 angstroms to about300 angstroms.

FIG. 13B schematically depicts another embodiment of a multi-layeredtape 119 that includes a substrate layer 125 formed from a polymericmaterial, e.g., as discussed in more detail above. The multi-layer tapecan further include a non-woven polymeric fabric layer 127 disposed overthe substrate layer 125. The non-woven polymeric fabric layer can beelectrically insulative, dissipative or conductive. Non-woven polymericmaterials suitable for used in this and other embodiments are discussedin more detail below.

In some embodiments, the non-woven polymeric layer includes a pluralityof electrically conductive inclusions (e.g., metal inclusions)distributed therein, e.g., in a manner discussed above. In someimplementations, the metal inclusions can have a variety of differentshapes. For example, some metal inclusions can have a shape (e.g., aneedle-like shape) that is suitable for primarily dissipatingelectromagnetic radiation incident thereon having a frequency in a rangeof about 1 MHz to about 40 GHz or in a range of about 1 MHz to about 10GHz, or in a range of about 1 MHz to about 2 GHz, or in a range of about1 MHz to about 1.5 GHz, while some other inclusions can have a differentshape (e.g., a flake-like shape) that is suitable for primarilyreflecting electromagnetic radiation incident thereon having a frequencyin a range of about 1 MHz to about 40 GHz or in a range of about 1 MHzto about 10 GHz, or in a range of about 1 MHz to about 2 GHz, or in arange of about 1 MHz to about 1.5 GHz.

In some embodiments, the density of the electrically conductiveinclusions (e.g., metal inclusions) distributed within the non-wovenfabric layer 127 is sufficiently high such that the metal inclusionsform an electrically conductive network so as to form, e.g., anelectrically conductive non-woven layer. In other embodiments, thedensity of the electrically conductive inclusions (e.g., metalinclusions) distributed within the non-woven fabric layer is less andthe inclusions are substantially separate from one another so as toform, e.g., a dissipative non-woven layer.

In other embodiments, the non-woven layer 127 is free of electricallyconductive inclusions.

In some embodiments, the multi-layered tape can provide shielding ofelectromagnetic radiation over a wide range of frequencies, e.g., in arange of about 1 MHz to about 10 GHz. While the thin metal layer canprovide effective shielding at relatively low frequencies (e.g.,frequencies less than about 10 MHz), the electrically conductivenonwoven layer and the polymeric substrate can provide effectiveshielding at higher frequencies (e.g., frequencies greater than about 10MHz). For example, the nonwoven layer and the polymeric substrate, aloneor in combination with each other, can provide effective shielding in afrequency range of about 500 MHz to about 1 GHz, in a range of about 500MHz to about 10 GHz, in a range of about 1 MHz to about 40 GHz, in arange of about 1 MHz to about 10 GHz, in a range of about 1 MHz to about2 GHz, or in a range of about 1 MHz to about 1.5 GHz.

FIG. 13C schematically illustrates a modified version of themulti-layered tape discussed above in connection with FIG. 13B in whicha thin metallic layer 133 (e.g., an aluminum foil layer) is disposedbetween an underlying polymeric substrate 135 and a non-woven fabriclayer 137. Similar to the non-woven fabric layer 127 discussed above inconnection with FIG. 13B, this non-woven layer 137 can be formed of apolymeric material, such those discussed above. While in someembodiments, the non-woven fabric layer includes a plurality ofelectrically conductive inclusions (e.g., metal inclusions) distributedtherein, in other embodiments the non-woven fabric layer 137 is free ofsuch inclusions.

FIG. 13D depicts schematically another multi-layered tape according toanother embodiment of the invention that includes a thin metallic layer143 (e.g., an aluminum foil layer) over a surface of which a non-wovenfabric layer 147 is disposed. In some embodiments, the thin metalliclayer and the non-woven fabric layer can be mechanically bonded to oneanother, as discussed in more detail below. The non-woven fabric layercan be electrically insulative, dissipative or conductive. In someembodiments, the non-woven fabric layer 147 includes a plurality ofelectrically conductive (e.g., metal) inclusions while in otherembodiments the non-woven fabric layer 147 is free of such inclusions.In some embodiments in which the non-woven fabric layer 147 includeselectrically conductive inclusions, the inclusions form aninterconnected network while in other such embodiments the inclusionsare substantially separate from one another.

The multi-layered tapes discussed above can be used, for example, toprovide shielding in a cable, as discussed in more detail below withrespect to FIG. 16. In such applications the multi-layered tapes canprovide numerous benefits. For example, multi-layered tapes according tothe embodiments schematically illustrated in FIGS. 13A, 13B, and 13C,13D can provide the benefit of reduced insertion loss when used in sucha cable. For example, when used to encircle conductors in a cable, thesubstrate layer, 115, 125, 135, provides a spacing between theconductive layer, e.g., metallic layer 117, 123, 133 and the conductorsencircled by the tape. The spacing between conductors and the conductivelayer can reduce insertion loss in the cable.

Multi-layered tapes according to the embodiment schematicallyillustrated in FIG. 13D can provide the benefit of shielding over a widefrequency range. For example, an insulative, dissipative, or conductivenonwoven layer can provide electromagnetic shielding at a differentfrequency range than a metallic layer. The combination of an insulative,dissipative, or conductive nonwoven layer and a metallic layer can thusprovide effective shielding over a wide range of frequencies.

The multi-layer tapes discussed above can be manufactured in a varietyof ways. By way of example, the polymeric substrate layer, e.g., layer115 in FIG. 13A, can be manufactured in accord with the methodsdiscussed above for producing tapes from polymer, e.g., fluoropolymer orpolyolefin, pellets. The non-woven polymeric fabric layer, e.g., layer127 in FIG. 13B, can be manufactured in accord with the methodsdiscussed in more detail below for producing non-woven materials. Thevarious layers, e.g., polymeric substrate layer, nonwoven fabric layer,and metallic layer can be bonded to their adjacent layer using varioustechniques. In some embodiments, the layers can be bonded using anadhesive or other bonding agents. In other embodiments, the layers canbe mechanically affixed or bonded to one another. For example, themetallic layer can be joined to a nonwoven layer by needlepunching, asdiscussed in more detail below. For another example, the polymeric layerand/or the nonwoven fabric layer can be thermally bonded to each otheror to the metallic layer by selectively heating portions of the layersto a temperature sufficient to melt the polymer components, e.g., byultrasonic welding or calender bonding.

In other examples, the polymeric layer and/or the nonwoven fabric layercan be thermally bonded to each other or to the metallic layer byultrasonic bonding. For example, the layers of material can be drawnbetween a horn, which provides high frequency sound waves, and a rotarycalendar, referred to as an anvil. The sound energy can generatelocalized heat through mechanical vibration at the embossing points ofthe anvil, thereby fusing the material.

Other exemplary embodiments of methods of manufacturing tapes aredisclosed in U.S. application Ser. No. 12/221,280, filed Aug. 1, 2008,entitled “Compositions for Compounding, Extrusion, and Melt Processingof Foamable and Cellular Fluoropolymers,” now issued as U.S. Pat. No.7,968,613, the teachings of which are incorporated herein by referencein their entirety.

Nonwovens

In another aspect, the invention provides nonwoven fabrics incorporatingelectrically conductive elements, e.g., electrically conductiveinclusions. The nonwoven fabrics can be used as tapes, which can be usedas an overall shield or as a shield for individual conductors or pairsof conductors, as discussed in more detail above. For example, FIG. 14schematically depicts a nonwoven fabric 120 including a plurality ofconductive fibrils 122. The conductive fibrils can be made of anysuitable electrically conductive material. In some embodiments, theconductive fibrils can be formed of a metal such as copper, silver,aluminum, gold bronze, tin, zinc, iron, nickel, indium, gallium, orstainless steel. In some embodiments the conductive fibrils can beformed of metal alloys, such as, for example, tin alloys, galliumalloys, or zinc alloys. In other embodiments, the conductive fibrils canbe formed of metal oxides, such as, for example, copper oxide, bronzeoxide, tin oxide, zinc oxide, zinc-doped indium oxide, indium tin oxide,nickel oxide, or aluminum oxide. In some embodiments, the conductiveelements incorporated into the nonwoven fabric can be in the form ofelectrically conductive fibers, such as monofilaments, yarns, threads,braids, bundles, chopped foil, e.g., tinsel, or combinations thereof.

The nonwoven fabric 120 can include interlocking layers or networks offibers, filaments, or film-like filamentary structures. In someembodiments, the nonwoven fabric 122 can be formed from webs ofpreviously prepared/formed fibers, filaments, films, or tapes processedinto arranged networks of a desired structure. In some embodiments, thepreviously prepared or formed fibers, filaments, or films can beproduced by extruding or otherwise processing the polymer compositionsdiscussed above, e.g., polymer compositions comprising conductiveinclusions.

For example, multi-filaments of yarns with individual filament diametersin the range of about 0.0005 to about 0.005, or in the range of about0.001 inches to about 0.002 inches can be chopped into staple fibers.The lengths of these staple fibers can vary. For example, in someembodiments the staple fibers can have a length in the range of about0.24 inches to about 3 inches. The staple fibers can be processed toform nonwoven fabric via various web forming processes.

In some embodiments, the nonwoven fabric 120 can include polymer fibersthat are bonded together by processes other than weaving or knitting. Avariety of polymers, e.g., polyolefins or fluoropolymers, includingperfluoropolymers, can be employed to form the fibers. By way ofexample, the fibers can be formed of any of FEP, MFA, PFA, PVF, PTFE,ETFE, ECTFE, PVDF. In some embodiments, some of the fibers are formed ofone polymer and the others are formed of another polymer.

Those having skill in the art will recognize that dry laid nonwovensinclude those nonwovens formed by garneting, carding, and/oraerodynamically manipulating dry fibers in the dry state. Nonwovens canalso be formed by extruding a polymer through a linear or circularspinnerette. The extruded polymer streams are then rapidly cooled andattenuated by air and/or mechanical drafting rollers to form filamentsof the desired diameter. The filaments can then be laid down onto aconveyor belt to form a web. The web can then be bonded to form aspunbonded web.

In other embodiments, nonwovens can also be formed by a melt blowingprocess. In such a process, a polymer can be extruded through a lineardie containing a plurality of small orifices. Convergent streams of hotair can then rapidly attenuate the extruded polymer streams to formfibers with extremely fine diameters. The attenuated fibers can then beblown by high velocity air onto a collector screen to form a melt-blownweb. The fibers in the melt-blown web are laid together by a combinationof entanglement and cohesive sticking.

In addition, wet laid nonwovens are well known to be formed from afiber-containing slurry that is deposited on a surface, such as a movingconveyor. The nonwoven web can be formed after removing the aqueouscomponent and drying the fibers. Hybrids of these nonwovens can beformed by combining one or more layers of different types of nonwovensby a variety of lamination techniques.

In some embodiments, the nonwoven fabric 120 preferably has a densityand thickness, and other mechanical and electrical characteristics,suitable for use as an insulating separator in telecommunicationscables. By way of example, in one embodiment, the density of thenonwoven fabric, with or without electrically conductive elements, canbe in a range of about 0.1 g/cm³ to about 9 g/cm³. For example, in someembodiments, the density of the nonwoven material can be less than about0.3 g/cm³, or less than about 1.2 g/cm³, or less than about 2 g/cm³, orless than about 9 g/cm³. The thickness of the nonwoven can be in therange of about 0.05 mm to about 5 mm. For example, in some embodiments,the thickness of the nonwoven can be in the range of about 0.05 mm toabout 2 mm. In other exemplary embodiments, the thickness of thenonwoven can be in the range of about 0.2 mm to about 1 mm. In otherexemplary embodiments, the thickness of the nonwoven can be in the rangeof about 1 mm to about 5 mm.

Exemplary embodiments of methods that can be used to form nonwovenfabrics are disclosed in U.S. application Ser. No. 12/586,658, filedSep. 25, 2009, entitled “Apparatus and Method for Melt Spun Productionof Non-Woven Fluoropolymers of Perfluoropolymers,” now published as USPublication No. 2011/0076907, the teachings of which are incorporatedherein by reference.

The nonwoven fabric 120 including electrically conductive fibrils 112can be formed in a variety of ways. In some embodiments, electricallyconductive elements 112 can be combined with a plurality of polymerfibers, e.g., polyolefin or fluoropolymer, such as perfluoropolymer,before or during the processing of the fibers into a nonwoven fabric. Inother embodiments, electrically conductive elements, such aselectrically conductive fibrils, can be applied to the nonwoven materialitself, e.g., by needle punching the fibrils into the nonwoven material.In exemplary methods of needlepunching, barbed needles can be punchedthrough layers of material, e.g., a metallic layer disposed on anon-woven layer. The needles hook tufts of fibers through the layers ofmaterial, bonding the layers together. For example, in an exemplaryembodiment of a needle loom 160 schematically depicted in FIG. 15A, aneedle board 161 including a plurality of needles 162 can be used tobond a first layer of material 164, e.g., a metallic layer, to a secondlayer of material 165, e.g., a nonwoven material. The needles 162disposed on the needle board 161 can be driven so as to enter and leavethe layers material 164, 165 while they pass between two plates commonlyreferred to as a bed plate 166 and a stripper plate 167. The layers ofmaterial 164, 165 can be pulled through the needle loom 160 by drawrollers 168, 169.

In other embodiments, electrically conductive elements can be applied toa nonwoven material by thermally bonding an electrically conductivematerial to the nonwoven material. For example, electrically conductivematerial, e.g., metal particles or chopped metal strands, or choppedmetal foil, can be bonded to regions of nonwoven web material bycalender bonding. FIG. 15 B schematically depicts an exemplaryembodiment of a calender bonding apparatus 170. The apparatus includes,for example, an embossed cylinder 172 and a smooth cylinder 173. A webof nonwoven material 174 passes between the cylinders. The cylinders172, 173 are heated, e.g., to a temperature sufficient to soften thepolymers used to form the nonwoven material. A plurality of electricallyconductive elements 175 can be applied to the nonwoven web 174 as itpasses through the apparatus 170. The web 174 with the electricallyconductive elements 175 disposed thereon is drawn between the heatedcylinders 172, 173. The embossed pattern on the embossed cylinder 172exposes portions of the web 174 to heat and pressure, thereby bondingthe electrically conductive elements 175 to the web 174.

In some embodiments, the nonwoven materials discussed above can exhibita sheet resistance in a range of about 1×10⁻⁵ ohms per square to about1×10⁵ ohms per square, or preferably about 10 ohms per square. As one ofskill in the art will appreciate, the sheet resistance of a materialwill change depending on the thickness of the material. For example,sheet resistance (ohms per square) multiplied by the material thicknessin centimeters equals the volume resistivity of the material (ohms-cm).As a result, the volume resistivity needed to achieve a given sheetresistance will depend on the thickness of the material in question. Forexample, a thicker material will provide the same volume resistivitywith a less conductive material as a thinner material that is moreconductive. As a more specific example, a tape with a thickness of0.0254 cm (0.010 inches) can have a volume resistivity of 0.254 ohms-cmand a surface resistance of 10 ohms per square. If the thickness of thetape is reduced to 0.0127 cm (0.005 inches), the volume resistivity mustbe reduced by half to 0.127 ohms-cm to achieve the same surfaceresistance of 10 ohms per square.

In some embodiments, the nonwoven materials discussed above can have ashielding effectiveness in a range of about 15 dB to about 90 dB, or ina range of about 15 dB to about 50 dB, or in a range of about 50 dB toabout 90 dB. Shielding effectiveness can be measured according to ASTMD4935-99: Standard Test Method for Measuring the ElectromagneticShielding Effectiveness of Planar Materials, the contents of which areincorporated herein by reference.

Cables

In another aspect, the invention provides cables, e.g.,telecommunications cables. The cables can include any of the tapes, theseparators and the nonwoven fabrics discussed above to provideelectromagnetic shielding of conductors disposed in the cable. In someembodiments, the cable can include various combinations of tapes,separators and nonwoven fabrics.

By way of example, FIG. 16 schematically illustrates a cable 130including two twisted pairs of conductors 132 and 134, and a tape 136that is wrapped around the conductors 132 and 134 to provideelectromagnetic shielding between the conductors 132 and 134.

As was discussed above, FIGS. 6A and 6B schematically illustrate otherexemplary embodiments of cables that include separators. Other exemplaryembodiments of cable in which separators according to the teachings ofthe invention can be employed are disclosed in U.S. application Ser. No.12/754,737, filed Apr. 6, 2010, entitled “High PerformanceSupport-Separators for Communications Cables Providing Shielding forMinimizing Alien Crosstalk,” now published as US Publication No.2010/0206609, the teachings of which are incorporated herein byreference in their entirety.

Cable Jackets

In another aspect, the invention provides a jacket for a cables, e.g., atelecommunications cable. In some embodiments, the jacket can include aplurality of electrically conductive inclusions, e.g., metal particles,that are distributed therein to provide shielding of electromagneticradiation. For example, the jacket can be formed from any of thepolymeric compositions disclosed herein. In another exemplaryembodiment, rather than or in addition to distributing metal inclusionswithin a cable jacket, an electrically conductive layer can be embeddedin the polymeric shell of the cable jacket. The electrically conductivelayer can be adapted to provide electromagnetic shielding of one or moreconductors.

By way of example, FIGS. 17A and 17B schematically depict a cable jacket140 according to one embodiment of the invention that has an elongatetubular shape, which extends from a proximal end 142 to a distal end144. The elongate tubular shape of the cable jacket forms a shell, e.g.,a polymeric shell, having an interior lumen 146 adapted for housing oneor more conductors. A plurality of metal inclusions 148 are distributedthroughout the cable jacket 140. While in some embodiments the metalinclusions 148 are distributed substantially uniformly within the bodyof the cable jacket 140, e.g., as depicted in the cross-sectional viewof FIG. 17B, in other embodiments, the spatial distribution of the metalinclusions can be non-uniform.

By way of example, in some embodiments, the density of the metalinclusions 148 in the proximity of the inner or outer surfaces, or both,of the wall of the jacket can be greater than a respective density inthe center of the wall of the jacket. As discussed in more detail below,the metal inclusions facilitate shielding the conductors disposed in thejacket from conductors in other cables, thereby minimizing andpreferably eliminating cross-talk between cables, i.e., aliencross-talk. In many embodiments, the cable jacket 140 is particularlyeffective in lowering alien cross-talk at a frequency range of about 1MHz to about 10 GHz between neighboring cables.

In this exemplary embodiment, the cable jacket 140 is formed of apolymeric material in which a plurality of metal inclusions 148, e.g.,metallic particles, are distributed. By way of example, in someimplementations, the cable jacket 140 comprises a polyolefin,fluoropolymer (e.g., PVDF, PVF, ECTFE, or ETFE), or a perfluoropolymer(e.g., FEP, MFA or PFA) and the metal inclusions are formed of a metalsuch as copper, silver, gold aluminum, bronze, tin, alloys of tin, zinc,alloys of zinc, iron, nickel, indium, alloys of indium, gallium, alloysof gallium, or stainless steel. In other embodiments, the inclusions canbe formed of metal oxides, such as, for example, copper oxide, bronzeoxide, tin oxide, zinc oxide, nickel oxide, zinc-doped indium oxide,indium tin oxide, or aluminum oxide. In some implementations, the cablejacket comprises two or more different polymers, e.g., a blend of two ofmore of FEP, MFA, and PFA. Further, in some cases, the metal inclusionscan exhibit a variety of different shapes and/or be formed of differentmetals.

In some embodiments, one type of the metal inclusions primarily reflectelectromagnetic radiation within a frequency range (e.g., a frequencyrange of about 1 MHz to about 10 GHz) incident thereon while the othertype of metal inclusions primarily absorb the incident radiation in thatwavelength range. In this manner, effective shielding of conductors,e.g., twisted-pair wires, housed in the cable jacket can be achieved.

By way of example, in this exemplary embodiment, the metal inclusions148 can include two types, one of which exhibits a needle-like shape andthe other a flat flake-like shape, as shown in FIGS. 3A and 3B, and asdiscussed in more detail above.

In some embodiments, the metal inclusions 148 can comprise a volumefraction of the cable jacket 140 in a range of about 1% to about 40%, orin a range of about 2% to about 30%, or in a range of about 3% to about20%, or in a range of about 4% to about 15%, or in a range of about 5%to about 10%.

In some embodiments, the polymer, e.g., fluoropolymer, polyolefin, orcombinations thereof, can comprise at least about 30%, or at least about40%, or at least about 50%, or at least about 60%, or at least about70%, or at least about 80%, or at least about 85%, or at least about90%, or at least about 95%. of the volume of the cable jacket.

In some embodiments, the metal inclusions 148 can comprise a weightpercent of the cable jacket in a range of about 1% to about 30%, or in arange of about 5% to about 20%, or in a range of about 5% to about 15%,or in a range of about 10% to about 15%.

The above cable jacket 140, or other pre-formed cellular articles,having a plurality of metal inclusions can be manufactured in a varietyof ways. In one exemplary method of manufacturing the separator 10, aplurality of polymer pellets in which metal inclusions are incorporated,such as the pellets discussed above, can be melted and the moltenpellets can be extruded to form the cable jacket 140.

FIGS. 18A and 18B schematically depict a cable jacket 150 according toanother exemplary embodiment of the invention that has an elongatetubular shape. The elongate tubular shape of the cable jacket forms ashell 152, e.g., a polymeric shell, having an inner lumen 154 adaptedfor housing one or more conductors. A metal layer 156 is embedded in thecable jacket 150. The thickness of the metal layer can be, e.g., in arange of about 0.001 inches to about 0.010 inches. A number of metalscan be utilized to form the metal layer 156. By way of example, themetal layer can be formed of any of copper, silver, aluminum, copper,gold, bronze, tin, zinc, iron, nickel, indium, gallium, or stainlesssteel.

In some embodiments, the metal layer can be a continuous metal layerthat extends along the length of the jacket from a proximal end to adistal end thereof to provide electromagnetic shielding between cables,e.g., as depicted in FIG. 18A. In other embodiments, the metal layer canbe discontinuous. For example, the metal layer can be a checkered layerof metal 158, e.g., as depicted in FIG. 18B. In some cases, the metallayer can comprise at least about 30%, or at least about 40%, or atleast about 50%, or at least about 60%, or at least about 70%, or atleast about 80%, or at least about 90%, or at least about 95% of thesurface area of the cable jacket.

The above cable jackets can be manufactured in a variety of ways. In oneexemplary method of manufacturing the cable jackets, the metal layer canbe co-extruded along with a plurality of fluoropolymer pellets to formthe jacket.

Examples

To further elucidate various aspects of the invention, the followingworking examples are provided. The examples are provided only forillustrative purposes and are not intended necessarily to presentoptimal practice of the invention and/or optimal results that may beobtained by practicing the invention.

Conductive elements were combined with base polymers in a meltcompounder and extruded into pelletized form. More specifically,aluminum (Al) pellets marketed under the trade designation Silvet220-20-E, aluminum flakes marketed under the trade designation K101 (600micron by 1000 micron rectangular pellets with a 25 micron thickness),stainless steel (SS) pellets marketed under the trade designation STAPAWM REFLEXAL 212/80, and copper powder marketed under the tradedesignation BR-83 UP COPPER were employed as conductive element. One ortwo of these conductive elements were incorporated into high densitypolyethylene (HDPE) and low density polytethylene (LDPE) base polymers,as shown in the following table, to generate pellets. The pellets werecast into dumbbell, rectangular, and circular plaques, and were testedfor various properties, as shown in the Table 1 below:

TABLE 1 Formulation 1 2 3 4 General Aluminum (Al) Al Flakes Al Flakes &Stainless Steel Description Pellets Al Pellets (SS) Pellets & Al PelletsSpecific 75% LDPE & 75% LDPE & 75% LDPE, 15% 75% LDPE, Recipe 25% SILVET25% K101 K101 Al Flakes 15% Beki-Shield 220-20-E Al Flakes & 10% SILVETGR75/C12-E/6 & Al Pigment 220-20-E 10% SILVET Al Pigment 220-20-E AlPigment Source SILBERLINE Transmet Transmet BEKAERT & CorporationCorporation & SILBERLINE SILBERLINE Specific 1.0396 1.0861 1.0641 1.0838Gravity Tensile (psi) 2892 1203 1960 1600 Elongation 55% 46% 64% 109% %Metallic 20% 28% 22%  19% Content Formulation 5 6 7 8 General Al PowderAl Powder & Copper Copper & Al Description SS Pellets Pellets Specific75% HDPE & 75% HDPE, 75% HDPE & 75% HDPE, Recipe 25% STAPA 10% STAPA 25%BR-83 UP 10% BR-83 UP WM WM COPPER COPPER, & REFLEXAL REFLEXAL 15%SILVET 212/80 212/80, & 15% 220-20-E Beki-Shield Al Pigment GR75/C12-E/6Source ECKART ECKART & ECKART ECKART & BEKAERT SILBERLINE Specific1.0693 1.0782 1.209 1.1149 Gravity Tensile (psi) 2719 3093 2802 3381Elongation 55% 36% 46% 46% % Metallic 20% 19% 25% 22% Content

One skilled in the art will appreciate further features and advantagesof the invention based on the above-described embodiments. Accordingly,the invention is not to be limited by what has been particularly shownand described, except as indicated by the appended claims. Allpublications and references cited herein are expressly incorporatedherein by reference in their entirety.

What is claimed:
 1. A tape for use in a communications cable,comprising: a flexible, polymeric sheet extending from a proximal end toa distal end; and a plurality of electrically conductive inclusionsdistributed throughout the polymeric sheet; wherein said polymeric sheetcan be curved or bent along its longitudinal axis so as to form a shapesuitable for at least partially surrounding one or more conductors. 2.The tape of claim 1, wherein the plurality of electrically conductiveinclusions comprises a plurality of metal inclusions.
 3. The tape ofclaim 2, wherein the plurality of metal inclusions comprises any ofsilver, aluminum, copper, gold, bronze, tin, zinc, iron, nickel, indium,gallium, stainless steel, and a combination thereof.
 4. The tape ofclaim 2, wherein the plurality of metal inclusions exhibits aneedle-like shape, a flake-like shape, or a combination thereof.
 5. Thetape of claim 3, wherein the plurality of electrically conductiveinclusions further comprises a plurality of carbon fibers.
 6. The tapeof claim 1, wherein the polymeric sheet comprises a polyolefin, afluoropolymer, or a combination thereof.
 7. The tape of claim 6, whereinthe fluoropolymer comprises a perfluoropolymer.
 8. The tape of claim 7,wherein the perfluoropolymer comprises any of FEP, MFA and PFA.
 9. Thetape of claim 1, wherein the electrically conductive inclusionscomprises a volume fraction of the tape in a range of about 1% to about40%.
 10. The tape of claim 1, wherein the electrically conductiveinclusions comprises a volume fraction of the tape in a range of about5% to about 10%.
 11. The tape of claim 1, wherein the polymeric sheet isfoamed.
 12. The tape of claim 1, wherein the tape has a thickness in arange of about 0.001 inches to about 0.02 inches.
 13. The tape of claim1, wherein said tape comprises a plurality of polymeric fibers.
 14. Thetape of claim 1, wherein said tape exhibits a DC electrical conductivityalong an axial direction in a range of about 1×10³ Siemens/meter toabout 3.5×10⁷ Siemens/meter.
 15. The tape of claim 1, wherein said tapeexhibits a sheet resistance in a range of about 1×10⁻⁵ ohms per squareto about 1×10⁵ ohms per square.
 16. A tape for use in a communicationscable, comprising: a polymeric substrate layer extending from a proximalend to a distal end; and a metallic layer dispersed over at least aportion of a surface of the polymeric substrate layer; wherein saidsubstrate layer and said metallic layer form a sheet that can be curvedor bent along its longitudinal axis so as to form a shape suitable forat least partially surrounding one or more conductors.
 17. The tape ofclaim 16, wherein the metallic layer comprises a plurality of metalinclusions.
 18. The tape of claim 17, wherein the plurality of metalinclusions comprises any of silver, aluminum, copper, gold, bronze, tin,zinc, iron, nickel, indium, gallium, stainless steel and combinationsthereof.
 19. The tape of claim 17, further comprising a plurality ofcarbon fibers.
 20. The tape of claim 16, wherein the polymeric substratelayer comprises a polyolefin, a fluoropolymer, or a combination thereof.21. The tape of claim 20, wherein the fluoropolymer comprises aperfluoropolymer.
 22. The tape of claim 21, wherein the perfluoropolymercomprises any of FEP, MFA, PFA, PVF, PTFE, ETFE, ECTFE, PVDF, and acombination thereof.
 23. The tape of claim 16, wherein the electricallyconductive inclusions comprises a volume fraction of the tape in a rangeof about 1% to about 40%.
 24. The tape of claim 16, wherein thepolymeric substrate layer is foamed.